"You shall not take the name of the Lord your God in vain (Heb. shav), for the Lord will not leave him unpunished who takes His name in vain. (Exodus 20:7)
'You shall not take the name of the Lord your God in vain (Heb. shav), for the Lord will not leave him unpunished who takes His name in vain. (Deuteronomy 5:11)
Muslims get very upset if anyone denigrates the name of Allah or Muhammad - the man they believe to be his last prophet. Unfortunately, Christian believers are nowhere near as zealous about respecting the name of their God.
Perhaps because it doesn't seem like an extremely serious infraction many of us have let this one slide - brushed it aside to the point that we have become virtually immune to the millions of empty, worthless reference to our God made every day. In fact, it is not at all uncommon for believers to pepper their own speech with both mindless and pointless references to G5od. OMG or 'Oh Lord' being prime examples.
However, what we need to remember is that not taking the Lord's name in vain was not 36th on a list of 500 commandments, but the third on an extremely short list of ten. Thus it should come as no surprise that God takes a very dim view of people who break this commandment. The most obvious infraction is when someone blasphemes (speaks impiously or irreverently of God - utters profanities) or curses in His name. As the Bible says
My enemies have reproached me all day long; Those who deride me have used my name as a curse. (Psalms 102:8 NASB)
Think about it for a moment. How many people would be okay with someone using their mother's, or spouse's name as a curse word or even to add emphasis to something spoken. God doesn't like it either. In fact, blasphemy carried the ultimate penalty.
'Moreover, the one who blasphemes the name of the Lord shall surely be put to death; all the congregation shall certainly stone him. The alien as well as the native, when he blasphemes the Name, shall be put to death. (Leviticus 24:16 NASB)
The problem is that most assume that this prohibition is solely aimed at curse words or outright blasphemy. However, this rigid interpretation demonstrates a very superficial understanding of the verse. God's law applies to both our actions and our attitudes. For example, Christians who claim to be followers of Jesus, but do not act like it bring dishonor on His name.
You who boast in the Law, through your breaking the Law, do you dishonor God? For "The name of God is blasphemed among the gentiles because of you," just as it is written. (Romans 2:23-24 NASB)
Perhaps a closer look at the Hebrew word translated in vain will give us a deeper understanding of what the Father was prohibiting and why.
"In Vain" = Worthless (or waste of time)
In the Old Testament, the English vain has been translated from the Hebrew shav meaning empty. In English, vain generally means to no avail; fruitless; without real significance; Lacking substance or worth. (in other words - a waste of time). That 'in vain' is a good translation of shav is well illustrated by the following examples.
Now David had said, "Surely in vain (Heb. shav) I have guarded all that this man has in the wilderness, so that nothing was missed of all that belonged to him; and he has returned me evil for good. (1 Samuel 25:21 NASB)
Unless the Lord builds the house, They labor in vain (Heb. shav) who build it; Unless the Lord guards the city, The watchman keeps awake in vain (Heb. shav) It is vain (Heb. shav) for you to rise up early, To retire late, To eat the bread of painful labors; For He gives to His beloved even in his sleep. (Psalms 127:1-2 NASB)
"Bring your worthless (Heb. shav) offerings no longer, Incense is an abomination to Me. New moon and Sabbath, the calling of assemblies - I cannot endure iniquity and the solemn assembly. (Isaiah 1:13 NASB)
In vain (Heb. shav) I have struck your sons; They accepted no chastening. Your sword has devoured your prophets Like a destroying lion. (Jeremiah 2:30 NASB)
And you, O desolate one, what will you do? Although you dress in scarlet, Although you decorate yourself with ornaments of gold, Although you enlarge your eyes with paint, In vain (Heb. shav) you make yourself beautiful. Your lovers despise you; They seek your life. (Jeremiah 4:30 NASB)
"You have said, 'It is vain (Heb. shav) to serve God; and what profit is it that we have kept His charge, and that we have walked in mourning before the Lord of hosts? (Malachi 3:14 NASB)
Note that shav is also used to signify lies or falsehood. See for example, Psalms 12:2, Isaiah 59:4, Jeremiah 23:25, Lamentations 2:14, Ezekiel 13:7 etc.
The Importance of Names in Biblical Times
When you consider that the Hebrew shav means worthless (see Isaiah 1:13 above), then the third commandment says '"You shall not take the name of the Lord your God worthlessly".
In other words without very good reason, which is a long way from outright profanity or blasphemy.
But why is this?
During Biblical times names were extremely important. They didn't just designate who a person was but gave many clues as to the person's attributes, character, reputation etc.
Occasionally names were tied in with prophecies as when Isaiah's older son (the one he took with him when he first went to meet king Ahaz) was called Shear-jashub (Isaiah: 7:3) which means "a remnant returns". In the spirit of typology, the prophecy had a double meaning - it referred to the remnant that returned from captivity in Babylon and the remnant that will be saved in the future. See Typology
In Hosea 1:4-9 the Lord told the prophet (a contemporary of Isaiah) what to name three of his children. All three names were prophetic messages. See The Virgin Shall Conceive.
Names Also Signified Authority
Consider the messenger - someone that might have been ignored or jeered had he not come in the name of the king. But the emissary had all the authority of the throne behind him which meant that people sat up and paid attention.
David certainly understood what it meant to come in the Lord's name. When he faced Goliath he told the giant,
"You come to me with a sword, a spear, and a javelin, but I come to you in the name of the Lord of hosts, the God of the armies of Israel, whom you have taunted. (1 Samuel 17:45 NASB)
We name false gods and by doing so we decide who they are and what their character and reputation should be. God brought the animals for Adam to name signifying his authority over them, which is why we did not give the Father a name of our choosing but He revealed His name to us. In Exodus 3 when God told Moses at the burning bush that he was to was to go to the Pharaoh, and bring the sons of Israel out of Egypt?, Moses asked God what he should say to the people if asked what the name of one who had sent him to Egypt.
The Father's reply has reverberated back and forth over the centuries since they were first spoken. He replied
God said to Moses, "I AM WHO I AM"; and He said, "Thus you shall say to the sons of Israel, 'I AM has sent me to you.'"
Although He went on to say He was the God of their fathers, the God of Abraham, the God of Isaac, and the God of Jacob, He first named himself as the sovereign, self-existent one.
The Father's Name
The very first words of the Lord's prayer are "'Our Father who is in heaven, Hallowed be Your name." On Pentecost Peter proclaimed to the crowd that there was no other name under heaven which they would be saved." (Acts 4:12). Paul followed suit when he wrote to the Romans that "everyone who calls on the name of the Lord will be saved" (Romans 10:13)
"I have manifested Your name to the men whom You gave Me out of the world; they were Yours and You gave them to Me, and they have kept Your word. (John 17:6 NASB)
and I have made Your name known to them, and will make it known, so that the love with which You loved Me may be in them, and I in them." (John 17:26 NASB)
As commentator Albert Barnes wrote "The word 'name' here includes the attributes or character of God. By making God's character, law, will, and plan of mercy known Jesus had revealed God to His disciples.
In view of the above is it any wonder that the name of the Lord is exalted throughout the Scriptures. For example,
If you are not careful to observe all the words of this law which are written in this book, to fear this honored and awesome name, the Lord your God, (Deuteronomy 28:58 NASB)
O Lord, our Lord, How majestic is Your name in all the earth, Who have displayed Your splendor above the heavens! (Psalms 8:1 NASB)
Some boast in chariots and some in horses, But we will boast in the name of the Lord, our God. (Psalms 20:7 NASB)
Ascribe to the Lord the glory due to His name; Worship the Lord in holy array. (Psalms 29:2 NASB)
O magnify the Lord with me, And let us exalt His name together. (Psalms 34:3 NASB)
Note: The name of God in the Old Testament was spelled YHWH in the Hebrew Bible (See why). The name was considered so sacred that it was not to even be read or spoken aloud. Thus over time the correct pronunciation of YHWH has been forgotten. Note: the Jews don't even write the word 'God. Instead they write G-D
However, this commandment does not mean that we are to avoid the Father's name altogether, but that we must not misuse it is any way. God's name should never be used to spice up a conversation or as an exclamation.
Our Mindless Use of God's Name
However, this also means that most of us are in very big trouble because we mindlessly use numerous phrases that, if taken literally, invoke God but, in reality, just fall out of our mouths without any real meaning. For example, how often do we say "God help us" or "God have mercy" when we are not literally appealing to the Father. Most of the time they are just words. As pastor Greg Koukl says
If you want an example of a vain and empty use of God's name, here it is. I'm sure people are wondering how I could criticize the use of "God bless you" as if it's on par with "oh god" or even "goddamn it." My response is this. What is it that most Christians mean when they say God bless you? I'll tell you. This is the Christian way of saying "Have a nice day." They mean "Goodbye."
How many of you who use this phrase consciously invoke a blessing whenever you say this? When someone sneezes and you say "God bless you" or when somebody leaves and you say "God bless you" are you really consciously invoking a blessing? I don't think most people are doing that. And frankly, even when I used to say this I wasn't thinking of invoking a blessing...
We're not really invoking a blessing. We're not saying anything at all. We're making nice Christian noises... and we're using God's name in a vain and empty fashion. 
Christians throw around the phrase "Praise the Lord" more times than I can count. However, much of the time it is simply pious sounding devoid of real meaning - an empty cliché said without giving the matter any thought. We would be well advised to avoid doing so unless we really mean what we're saying in which case it would probably not be 'in vain'.
What The Bible Says About Taking Oaths
How many times have you heard someone say "I swear to God that... " after making a mild or barely consequential declaration. Unfortunately, this phrase has also become one more of those trite clichés that roll off people's tongues without any thought behind the words.
It is true that oaths taken in the Lord's name were not unknown in the Scriptures.
When Abraham sent his servant to find a wife of Isaac, he made his servant swear to something he would not do.
and I will make you swear by the Lord, the God of heaven and the God of earth, that you shall not take a wife for my son from the daughters of the Canaanites, among whom I live, (Genesis 24:3 NASB)
Bathsheba reminded David that he swore to her "by the Lord your God" to make her son Solomon his heir.
She said to him, "My Lord, you swore to your maidservant by the Lord your God, saying, 'Surely your son Solomon shall be king after me and he shall sit on my throne.' (1 Kings 1:17 NASB)
In the first book of Kings, Solomon swore he would have Adonijah executed for his challenge to the throne.
Now therefore, as the Lord lives, who has established me and set me on the throne of David my father and who has made me a house as He promised, surely Adonijah shall be put to death today." (1 Kings 2:24 NASB)
When Saul threatened to kill his son Jonathan, the people swore they would not allow it.
But the people said to Saul, "Must Jonathan die, who has brought about this great deliverance in Israel? Far from it! As the Lord lives, not one hair of his head shall fall to the ground, for he has worked with God this day." So the people rescued Jonathan and he did not die. (1 Samuel 14:45 NASB)
In the second book of Kings, Elisha twice swore not to leave Elijah
Then Elijah said to him, "Please stay here, for the Lord has sent me to the Jordan." And he said, "As the Lord lives, and as you yourself live, I will not leave you." So the two of them went on. (2 Kings 2:6 NASB)
However, the Father prohibited taking false oaths
You shall not swear falsely by My name, so as to profane the name of your God; I am the Lord. (Leviticus 19:12 NASB)
In other words, the Israelites whose world was governed by law, the Father who knew they would take oaths anyway regulated the practice, directing them to only to make oaths they were going to keep and that only in His name. Bearing false witness carried a stiff penalty
"The judges shall investigate thoroughly, and if the witness is a false witness and he has accused his brother falsely, then you shall do to him just as he had intended to do to his brother. Thus you shall purge the evil from among you. "The rest will hear and be afraid, and will never again do such an evil thing among you. (Deuteronomy 19:18-20 NASB)
"I will make it (A curse) go forth," declares the Lord of hosts, "and it will enter the house of the thief and the house of the one who swears falsely by My name; and it will spend the night within that house and consume it with its timber and stones." (Zechariah 5:4 NASB)
In their strict adherence to the letter of the law, the scribes and Pharisees apparently permitted taking false oaths in the name of numerous other things. However, in Matthew 5, Jesus reiterated that vows to the Lord had to be fulfilled. However, He went on to correct this attempt to bypass the command in Leviticus 19:12 by reminding them that everything that they swore by was part of God's creation. Thus even when swearing by heaven, earth, Jerusalem, or even their heads they were swearing by God - and the oath had to be honored.
Again, you have heard that the ancients were told, 'You shall not make false vows, but shall fulfill your vows to the Lord.' "But I say to you, make no oath at all, either by heaven, for it is the throne of God, or by the earth, for it is the footstool of His feet, or by Jerusalem, for it is the city of the Great King. "Nor shall you make an oath by your head, for you cannot make one hair white or black. "But let your statement be, 'Yes, yes' or 'No, no'; anything beyond these is of evil. (Matthew 5:33-37 NASB)
In other words, like in many other issues we are held to a higher standard. See target="_blank" onClick='alert("ON-site link will open in a new window. To return here, simply close the new browser window.")'Jesus and The Law. In an extremely unambiguous statement, Jesus tells us not to swear at all which obviously includes legal matters. The equally forthright James added,
But above all, my brethren, do not swear, either by heaven or by earth or with any other oath; but your yes is to be yes, and your no, no, so that you may not fall under judgment. (James 5:12 NASB)
In this chapter after exhorting those who were suffering under various wrongs to exercise patience, he tells them that "above all" they should not swear with any oath. The "above all" shows how serious he considered the matter,
Improper Use of The Name 'Jesus'
The Significance of 'Jesus'
Jesus is the common Greek form of the Hebrew name Joshua - a transliteration of Hebrew Yehoshua, literally "the Lord is salvation." It was the name that the angel Gabriel commanded Joseph to name Mary's child.
She will bear a Son; and you shall call His name Jesus, for He will save His people from their sins. (Matthew 1:21 NASB)
And as Matthew went on to say
Now all this took place to fulfill what was spoken by the Lord through the prophet: "behold, the virgin shall be with child and shall bear a Son, and they shall call his name Immanuel," which translated means, "God with us." (Matthew 1:22-23 NASB)
Matthew was referring to Isaiah's prophecy made approximately 700 years earlier. Isaiah prophesied about a virgin who would "conceive and bear a Son, and shall call His name Immanuel" (7:14). This confuses some because no one ever called Jesus Immanuel. However just a couple of chapters later in prophesying about the Messiah, Isaiah also said "His name will be called Wonderful Counselor, Mighty God, Eternal Father, Prince of Peace." (Isaiah 9:6 NASB)
None of which were literal names but rather described who Jesus was. In other words, "Immanuel" was not intended to be Jesus' proper name but told us what He would accomplish.
Jesus - Name Above All Names
In other words, the name Jesus is synonymous with God's love and His offer of eternal life. See The Message of the Bible
And that is not all.
The Bible tells us that because He humbled Himself by becoming obedient to the point of death "God highly exalted Him, and bestowed on Him the name which is above every name". And "at the name of Jesus every knee will bow, of those who are in heaven and on earth and under the earth, and that every tongue will confess that Jesus Christ is Lord, to the glory of God the Father". See Philippians 2:8-11
All of which makes it extremely odd that Jesus is pretty much the only religious (or even non-religious) figure whose name is casually used by thousands of people as an exclamation or a swear word. Using 'Mohammed', 'Krishna', or 'Buddha' in the same way would seem very disrespectful to most people. But for some strange reason throwing 'Jesus Christ' around like so much confetti doesn't seem to bother them. And when have you ever heard anyone use 'Joseph Smith', 'Bill Gates', 'Isaac Newton', or even 'Adolf Hitler' to spice up their conversation?
Even some atheists have been known to use 'Jesus Christ' in their conversations. Go figure!
This leads me to believe that whether they realize it or not, the fact that Jesus' name is the only one ever used is a tacit acknowledgment that He is the most unique personality in all of history. There is something about Him that has so imprinted itself onto our subconscious that it wont go away.
 Greg Koukl. Stand To reason Ministries. https://www.str.org/articles/the-vain-name#.XPvuwsTPw2w
The words in the Hebrew Old Testament contained no vowels. The Scribes knew what vowels to use in the pronunciation of the words by the construction of the consonants, the context, and memory. It was written this way until the fifth century when the Masoretes added the vowels under the consonants in their version of the Old Testament known as the Masoretic Text.
The name of God in the Old Testament spelled YHWH, was considered holy, and was not to be read aloud. Instead, when the Hebrews came upon YHWH, they would say ADONAY, which means "Lord." In order to indicate this substitution, the Masoretes placed the vowels of ADONAY or the English equivalent of e, o, and a under the consonants of YHWH. Later Christian translators mistakenly combined the vowels of ADONAY with the consonants of YHWH producing the word "Jehovah." The term is recognized to be a late hybrid form never used by the Jews.
As said by David Guzik in his commentary of Leviticus
So, only the High Priest was allowed to pronounce the holy name of God (Yahweh), and only once a year - on the day of atonement. The proper pronunciation of the name would be passed on from the high priest to his successor, with the former's last breath. This is why where was confusion for many years about the exact pronunciation of the Tetragrammaton (YHWH), some mistakenly pronouncing the name "Jehovah" instead of "Yahweh" or "Yah-veh."