ALSO SEE RELATED ARTICLES
Why Christians Are Deceived
That deception is so rampant in the church can be primarily attributed to just one underlying fact - the vast majority of Christians today are Biblically illiterate.
The Four Most Dangerous Mistakes Any Christian Can Make
1) Believe that we, or our pastor/denomination/spiritual leader cannot be fooled, 2) Attribute every personal testimony and “sign” as being of or from God, 3) Take Bible verses out of context and 4) believe that we, as Christians, are not to judge anything or any one. Not necessarily in that order.
Fraternizing With The Enemy
Few seem to realize that the Christians are commanded to separate themselves from those who teach and practice false doctrine
ON THIS PAGE
We Cannot Agree To Disagree When It Comes To Serious Error
How Jesus And The Apostles Dealt With Erroneous Beliefs
Essentials and Non Essentials. Truth and False Humility
The Shaky Ground of Questionable Beliefs
The earliest church in Jerusalem not only thrived but also impressed people on the outside who saw a selfless and unified church. As verse 47 says they found "favor with all the people".
They were continually devoting themselves to the apostles' teaching and to fellowship, to the breaking of bread and to prayer. (43) Everyone kept feeling a sense of awe; and many wonders and signs were taking place through the apostles. (44) And all those who had believed were together and had all things in common; (45) and they began selling their property and possessions and were sharing them with all, as anyone might have need. (46) Day by day continuing with one mind in the temple, and breaking bread from house to house, they were taking their meals together with gladness and sincerity of heart, (47) praising God and having favor with all the people. And the Lord was adding to their number day by day those who were being saved. (Acts 2:42-47 NASB)
Unfortunately we have come a long, long way from that.
In very many churches today few even know what the other congregant's names are much less what help or encouragement they need. While there are some friends among the congregation, most people are strangers to one another and remain so for years. Think about it, You walk into the church, greet those you know, say hello to a few others, engage in some small talk after the service (during the time of "fellowship"), and that's usually as far as it goes.
The larger the church, the more pronounced the isolation. In spite of the fact that many of them have professional 'greeters' at the doors who may not even ask your name (if they do, it is highly unlikely they will remember it five minutes later). While their hearts might be in the right place, their greeting amounts to little more than the salesperson who comes up to you in the store and asks if you "found everything all right".
See The Church... Then and Now. Chapter VII - Two Ways of "Doing Church"
Scroll down to 'They Can Obey The "One Another" Instructions In The Bible. '
But I digress.
Most Christian leaders agree that there should be unity in the church - often pointing to the New Testament passages that speak on the subject.
Not always the easiest thing to achieve.
Human nature being what it is when any group of people come together, their differing personalities, backgrounds, experiences, levels of education and other factors play a big part in how they react to situations, perceive things around them etc. etc. etc. Additionally people can all too often be self-serving, prone to gossip, form cliques, etc. The list goes on and on. This can often make achieving a harmonious relationships very difficult. To do so takes work - sometimes a lot of work.
However, showing care and compassion for other believers is a principle found throughout the New Testament. As Paul wrote
So, as those who have been chosen of God, holy and beloved, put on a heart of compassion, kindness, humility, gentleness and patience; bearing with one another, and forgiving each other, whoever has a complaint against anyone; just as the Lord forgave you, so also should you. Beyond all these things put on love, which is the perfect bond of unity. Let the peace of Christ rule in your hearts, to which indeed you were called in one body; and be thankful. (Colossians 3:12-15 NASB)
Do nothing from selfishness or empty conceit, but with humility of mind regard one another as more important than yourselves; do not merely look out for your own personal interests, but also for the interests of others. Have this attitude in yourselves which was also in Christ Jesus, who, although He existed in the form of God, did not regard equality with God a thing to be grasped, but emptied Himself, taking the form of a bond-servant, and being made in the likeness of men. (Philippians 2:3-7 NASB)
And there were plenty more exhortations to believers to treat each other like the family they are.
Be devoted to one another (Romans 12:10, admonish one another (Romans 15:14), care for one another (1 Corinthians 12:25), serve one another (Galatians 5:13), bear one another's burdens (Galatians 6:2), strive together for the faith (Philippians 1:27) teach and admonish one another (Colossians 3:16), comfort one another (1 Thessalonians 4:18 ), encourage one another (1 Thessalonians 5:11, Hebrews 3:13, 10:25), confess your sins to one another (James 5:16), pray for one another (James 5:16), stimulate one another to love and good deeds (Hebrews 10:24), be hospitable to one another without complaint (1 Peter 4:9), and have fellowship with one another (1 John 1:7).
Although it is impossible that we are going to like everyone we come into contact with, when it comes to other believers we need to remember what we have in common i.e. we have all been redeemed by Christ and have all been adopted as God's sons and daughters. We all belong to one family and although families do not always agree on everything the bond between them should remain unbroken. As Paul wrote,
For even as the body is one and yet has many members, and all the members of the body, though they are many, are one body, so also is Christ. For by one Spirit we were all baptized into one body, whether Jews or Greeks, whether slaves or free, and we were all made to drink of one Spirit. For the body is not one member, but many. (1 Corinthians 12:12-14 NASB)
Is not the bread which we break a sharing in the body of Christ? Since there is one bread, we who are many are one body; for we all partake of the one bread. (1 Corinthians 10:16-17 NASB)
There is one body and one Spirit, just as also you were called in one hope of your calling; one Lord, one faith, one baptism, one God and Father of all who is over all and through all and in all. (Ephesians 4:4-6 NASB)
Certainly our churches shouldn't be divided by racial, cultural, or social differences.
There is neither Jew nor Greek, there is neither bond nor free, there is neither male nor female: for ye are all one in Christ Jesus. (Galatians 3:28)
Although liking someone makes it easier we don't have to like them to care about them and their well being. We don't have to like them in order to help them if we are able. We don't have to like them to encourage them in their faith.
But there is another side to this.
While there is absolutely no question that we should never let differences like personality and ego cause disharmony among the brethren, the idea of unity that many Christian leaders preach and teach is not true unity intended by the Bible. For example, in his book the Purpose Driven Life, retired mega-church pastor Rick Warren wrote
"unity in the church is so important that the New Testament gives more attention to it than to either heaven or hell" and "Unity is the soul of fellowship" and if we destroy it we rip the heart out of Christ's body (Pg. 160)
"We share the same salvation, the same life, and the same future — factors far more important than any differences we could enumerate" (Pg. 161).
"But for unity's sake we must never let differences divide us. We must stay focused on what matters most — learning to love each other as Christ has loved us, and fulfilling God's five purposes for each of us and his church. Conflict is usually a sign that the focus has shifted to less important issues, things the Bible calls 'disputable matters' (Romans 14:1; 2 Timothy 2:23). When we focus on personalities, preferences, interpretations, styles, or methods, division always happens. But if we concentrate on loving each other and fulfilling God's purposes, harmony results. Paul pleaded for this: 'Let there be real harmony so there won't be divisions in the church. I plead with you to be of one mind, united in thought and purpose (1 Corinthians 1:10 NLT)" (Pgs. 161-162).
While the above statements sound very 'Christian' their fundamental flaw is in assuming that there is no truth that people are required to stand on and defend. You could scour the Scriptures for the next ten years without finding a single word about being united at the expense of truth. The problem is all too often what passes for "unity" is nothing but compromise. Ignoring critical life threatening areas in which we differ is simply papering over the rot in the walls. And here is a prime example,
An article on lastdaysministries.org says (All Emphasis Added)
It's not wrong to have differing opinions but its wrong to allow these opinions to divide and separate us.
When confronted with those who hold different views from us - from the nuclear arms race to speaking in tongues or the doctrine of eternal security - we're presented with a wonderful opportunity to check our motives. If our personal opinions hinder us from relating to a fellow Christian, then we're forced to conclude that our opinions are more important to us than fellowship with another brother or sister in Christ. 
The above quote mentions tongues as one of the areas of "different views". But is this a mere difference of opinion or are tongues as largely used today one more piece of evidence for the occult invasion of the church?
See Tongues.. and The "Second Blessing"
What few believers seem to realize is that tongues and the related phenomena have been seen throughout history in both pagan and heretical Christian movements without apparently ANY difference. Even worse is that if you watch certain videos in chapter 5 you will see that the jerking, the screaming, and the collapse, are exactly the same in voodoo rituals, people who have a 'kundalini awakening' (as taught in Hinduism), and Pentecostals all over the world. Can any Christian believe for one moment that God has bestowed the gift of the Holy Spirit on Christians, non-Christians, cults, and pagans without any discrimination whatsoever?
If interpretation of Scriptural texts is a matter of opinion God has given us a useless book and we may as well chuck our Bibles into the trash. We also need to note that none of the early apostles put wrong teachings into the area of "opinion" and let it go. Much to the contrary, they fought tooth and nail to defend the truth. In Paul's sometimes stern, sometimes sad letter to the Galatians, he wrote
But even if we, or an angel from heaven, should preach to you a gospel contrary to what we have preached to you, he is to be accursed! As we have said before, so I say again now, if any man is preaching to you a gospel contrary to what you received, he is to be accursed! (Galatians 1:8-9)
You foolish Galatians, who has bewitched you, before whose eyes Jesus Christ was publicly portrayed as crucified? (Galatians 3:1)
Note the false teachers Paul spoke about were not wearing black robes and sacrificing virgins on the altar but were Judaizers who had apparently persuaded some of the new Christians to keep the Mosaic law and be circumcised. Were Paul's efforts to counter the errors of these false teachers destroying unity, or was it that the false teachers were destroying the foundation of Christianity, lowering it to the outward ceremonial system of pre-Christ Judaism.
If everything is a matter of opinion and we have to shelve most of our differences and stay united, what in the world was the point of Paul's warning about "savage wolves" whom he predicted would arise from among the flock after his departure and "draw away the disciples after them"? Why was he urging the leaders to stay alert and watch out for these deceivers? Could it possibly be because he was warning the leaders that they needed to gear up for the knock-down-drag-out battles they would have with the powers of darkness?
Be on guard for yourselves and for all the flock, among which the Holy Spirit has made you overseers, to shepherd the church of God which He purchased with His own blood. "I know that after my departure savage wolves will come in among you, not sparing the flock; and from among your own selves men will arise, speaking perverse things, to draw away the disciples after them. "Therefore be on the alert, remembering that night and day for a period of three years I did not cease to admonish each one with tears. (Acts 20:28-31 NASB)
Now I urge you, brethren, keep your eye on those who cause dissensions and hindrances contrary to the teaching which you learned, and turn away from them. For such men are slaves, not of our Lord Christ but of their own appetites; and by their smooth and flattering speech they deceive the hearts of the unsuspecting. (Romans 16:17-18 NASB)
Now we command you, brethren, in the name of our Lord Jesus Christ, that you keep away from every brother who leads an unruly life and not according to the tradition which you received from us. (2 Thessalonians 3:6 NASB)
The fact of the matter is that God never intended us to be unified with everyone. Unity is an agreement of sorts - a oneness of mind and purpose. As Amos once wrote "Can two walk together, except they be agreed?" Quite simply we cannot be agreed with everyone.
And it goes much further.
Christians are commanded to separate themselves from those that believe and teach false doctrine. They are to refuse to have fellowship with those who cross over the line. It is far better to be divided by truth than united in error. When Christians obey the Bible and separate themselves from heretics, they are actually promoting genuine Christian unity by standing together against heresy.
We Cannot Agree To Disagree When It Comes To Serious Error
Does anyone seriously think that learning the ways of the pagan world around us is NOT going to affect salvation when God so clearly stated "... come out from their midst and be separate," says the Lord. "and do not touch what is unclean; And I will welcome you. (2 Corinthians 6:17) The obvious implication being that if we do not separate ourselves from the world, we will not be received, i.e. not saved.
Believers are turning in ever increasing numbers to mystical practices such as Walking Labyrinths (Labyrinths were 'discovered' in a Catholic church but have their roots in pagan practices) and Contemplative Prayer based squarely on ideas borrowed heavily from Hindu and Buddhist traditions.
Many are part of the Word of Faith/Prosperity Doctrine Movements and/or encourage their congregations to be "Slain In The Spirit" or speak in '’Tongues'. Other churches promote "courses" such as the Alpha Course and the Purpose Driven Program - the first being occult driven, the second offers a shallow incomplete gospel that is woefully inadequate to save, all the while introducing believers to a wide variety of potentially very dangerous people, ideas, and practices etc.
More "liberal" churches that have begun to question or even openly deny the Bible being God's inerrant and absolutely infallible word to mankind now condone homosexuality or same-sex unions.
Every born again believer has the right, nay, the responsibility, to stand up for the truth. Thus a true believer who finds himself among men who profess to be Christians but whose teaching are conflict with the Word of the Lord has to abide by a two step process. See more on ...
See Fraternizing With The Enemy
We tend to look on confrontation as something to be avoided at all cost, but the Bible's instructions on how to deal with those who teach and practice false doctrine in the church are very explicit. It is a two step process. The heresy has to be actively confronted and, if not repented of, has to be shunned. The duty of every true believer towards those who profess to be Christians but deny the Word of the Lord, is to come out from among them. Leaving, or separating oneself from apostasy and heresy is not optional, but commanded.
How Jesus And The Apostles Dealt With Erroneous Beliefs
When dealing with the Pharisees who were respected religious leaders of the day, Jesus' language can only be called 'harsh'. He called them hypocrites, children of hell, blind guides, fools and blind, serpents, and a generation of vipers. Sadly, His words apply to many religious leaders of today.
"You brood of vipers, how can you, being evil, speak what is good? For the mouth speaks out of that which fills the heart. (Matthew 12:34)
"Woe to you, scribes and Pharisees, hypocrites! For you are like whitewashed tombs which on the outside appear beautiful, but inside they are full of dead men's bones and all uncleanness. (Matthew 23:27)
"You serpents, you brood of vipers, how will you escape the sentence of hell? (Matthew 23:33)
John, the "apostle of love" did not mince any words when speaking of people who claimed to know Jesus, but did not obey Him. He flat out called them "liars".
By this we know that we have come to know Him, if we keep His commandments. The one who says, "I have come to know Him," and does not keep His commandments, is a liar, and the truth is not in him; but whoever keeps His word, in him the love of God has truly been perfected. By this we know that we are in Him: (1 John 2:3-5)
Paul called the Colossians to unity and holiness (Colossians 3:8-15) but that did not mean that the Colossians were simply to love and be patient with each other, for his very next words were...
Let the word of Christ richly dwell within you, with all wisdom teaching and admonishing (Gr. noutheteo) one another with psalms and hymns and spiritual songs, singing with thankfulness in your hearts to God. (Colossians 3:16)
The word translated admonish, is the Greek noutheteo, which means to reprove or warn, which Paul uses several times. He not only admonished many of the churches he was involved with, but instructed many of them to admonish each other.
The epistles also show that he publicly refuted teachings that deviated from God's word.. As he told Timothy
The Lord's bond-servant must not be quarrelsome, but be kind to all, able to teach, patient when wronged, with gentleness correcting those who are in opposition, if perhaps God may grant them repentance leading to the knowledge of the truth, and they may come to their senses and escape from the snare of the devil, having been held captive by him to do his will. (2 Timothy 2:24-26)
When Paul advised gentleness, it did not mean that Timothy was never to confront those who opposed them but that he was to do it with kindness.
See The Four Most Dangerous Mistakes Any Christian Can Make
1) Believe that we, or our pastor/denomination/spiritual leader cannot be fooled, 2) Attribute every personal testimony and 'sign' as being of or from God, 3) Take Bible verses out of context and 4) believe that we, as Christians, are not to judge anything or any one. Not necessarily in that order.
Essentials and Non Essentials. Truth and False Humility
No question that here are primary matters on which we have to be agreed - and secondary matters that should not keep us from being united. Matt Slick, President and Founder of the Christian Apologetics and Research Ministry says the following...
It is all right to have differences of opinion on the non-essential matters like worship styles or days, pre-trib rapture, post-trib rapture, Arminianism, Calvinism, etc. Whether you believe one or the other, do not affect salvation. Yet far too many Christians use these non-essential differences as justification for division and sometimes even insight (incite?) anger. When this occurs, the love of God in our hearts is sacrificed to our pride. Instead of saying to one another, "I am right and you are wrong," we should be saying something like, "It is certainly possible that you are correct.
He goes on to ask "Should we not sacrifice our "perfect" opinion on a biblical matter for being gracious to another brother or sister in Christ?" 
I certainly would not want to incite a riot over completely non essential matters but, I am not sure why in the world I would want to concede that the other person might be right - a position that assumes that the truth cannot be known from God's word. However, do remember that if you ignore another believer's possibly dangerous beliefs and/or practices you are certainly not doing them any favors.
Steven J. Cole on Bible.org (Emphasis Added)
We should welcome into church membership all whom Christ has saved as long as those with differing views on secondary matters agree not to cause factions over those differences. While we may hold differing views on baptism, charismatic gifts, prophecy, etc. these should not keep us from being one body in Christ. For this reason, we allow those who do not share our Baptist views on baptism to join this church as long as they don't promote or teach their different views here. And, we restrict the office of elder to those who hold to our Baptist views. The same is true of those who hold to the validity of the charismatic gifts for today. We are skeptically cautious regarding most modern expressions of the gifts of tongues, interpretation of tongues, healing, miracles, and prophecy. Those who hold a different view are free to join us as long as they do not promote their views and cause division.
He also says that there are "three broad levels" of Bible doctrine (Emphasis Added)
(a) Essential truths, necessary for salvation. To deny any of these would be heresy and a denial of the faith. These include: The inspiration and authority of the Bible; the trinity; the full deity and humanity of Jesus Christ; His substitutionary death on the cross; His bodily resurrection and second coming; and, salvation by grace through faith alone, apart from works. 
I am sorry, but someone is going to have to show me where the Bible says that belief in the Trinity is essential to salvation. You will not be able to because that 'condition' is entirely man made i.e. does not exist in the Scriptures. In fact every passage that is quoted in favor of the Holy Spirit being the 'third person' of the Trinity does no such thing. And that DOES NOT in any way diminish the divinity of the Holy Spirit. The pronoun 'He' that the English New Testament uses for the Holy Spirit only reads that way because the original Greek word was translated according to pre-bias and can be translated she, it or them in English. And there is more - lots more including the Greek philosophers who had great influence on the council of Nicea and brought their pagan ideas with them. See Is God a Trinity?
Additionally, while there is no question that we cannot do anything to earn our own salvation other than have the faith that Jesus paid the price for our sins. However, one also has to remember what the author of Hebrews categorically stated
Pursue peace with all people, and the holiness without which no one will see the Lord. (Hebrews 12:14 NASB) What is Holiness
and James added works to faith and holiness
What use is it, my brethren, if someone says he has faith but he has no works? Can that faith save him? (James 2:14 NASB) person is saved through faith alone, one has to be careful here said faith without works is dead.
See Why Christians are Deceived
The reasons that so many modern day Christians are deceived are numerous. They believe they should be "united", and are commanded to "love". They do not want to be labeled "heresy hunters", accused of quenching the spirit, or found guilty of 'touching' the Lord's anointed etc. etc.
Questionable And Potentially Dangerous Beliefs
Some of the issues usually categorized as non-essential do not necessarily affect one's standing before God in the here and now but could at some point negatively impact ones salvation
The Pre-Tribulation Rapture: If you one of those people that have been taught that you will be 'raptured' away to heaven before all hell breaks loose, you are in for the shock of your life. Whether the Rapture will take place before or after the Great Tribulation has no bearing on salvation. Not now at any rate. But it is very possible that it will in the future. Let me explain.
If the Pre-Tribulation view is correct and believers will be raptured away to heaven before all hell breaks loose, then the Great Tribulation is purely of academic interest to the Christian - of little consequence. If, however, the Post-Tribulation view is correct, it means the Church has yet to experience a period of intense persecution and tribulation. As said by pastor Tim Warner...
"Some say it really doesn't matter if Jesus is coming before or after the tribulation, as long as we are "ready." They think we should all just agree to disagree, and love one another. But, "ready" is a relative term! It begs the question, "ready for what?" There is a huge difference between being ready to be gently whisked away to heaven on a pillow, and being ready to become a martyr at the hands of Antichrist! Is surface harmony worth the risk of huge numbers of believers being caught totally unprepared spiritually, emotionally, and physically?
See The End Of The Age Part V... The Rapture
The reasons we cannot and should not trust in the Rapture taking place before the tribulation.
Eternal Security or Once Saved Always Saved is preached as Biblical truth even in many conservative churches. Proponents believe that once a person has made the once and for all decision to "accept" Christ as savior, they are in the enviable position of being eternally secure in their salvation because there is not the slightest chance of slipping from His hand. Some carry this doctrine to ridiculous lengths even teaching that since they cannot be 'unforgiven'. In other words, believers can live the rest of their lives just as they please and still remain saved. There will be no repercussions other than possibly losing a reward or two. (Charles Stanley used to preach this perverted Gospel) See Rewards in Heaven
There is no question that most who teach eternal security also teach that only those who continue living holy lives will enter the Lord's presence. Unfortunately, there are all too many people that do not take this warning seriously. Human nature is human nature and if a person thinks they can have their cake and eat it too - why wouldn’t they? In other words, they figure that if eternal security is true and there is no fear of serious eternal consequences then why shouldn't they live their lives on earth just as they please?
See Once Saved, Always Saved. Part I - Eternal Life: Promise or Possession?
When the Gospel Becomes a Lie - Part III of Calvinism
And There are Plenty Of Related Articles here - A Question Of Salvation
 Floyd McClung. True & False Unity. Are We Fighting The Wrong Battles? https://www.lastdaysministries.org/Groups/1000087910/
 Matt Slick. The need for unity in the church. https://carm.org/need-unity-church
 Steven J. Cole. The Unity of the Church. https://bible.org/seriespage/lesson-4-unity-church-john-1722-23-1-cor-1213-eph-41-6-13