You shall not take the name of the Lord your God in vain, for the Lord will not hold him guiltless who takes His name in vain. (Exodus 20:7; Deuteronomy 5:11)

The Law of Moses, including the Ten Commandments, was taken away as law when Christ died on the cross (Colossians 2:13-17). But that does not mean we are free to take the name of the Lord in vain, that is, to use it disrespectfully, as a common byword. We must not be guilty of blasphemy (Colossians 3:8; 2 Timothy 3:2). Although blasphemy sometimes denotes "slander, detraction, speech injurious to another's good name" (Thayer. 102), it also describes "impious and reproachful speech injurious to divine majesty" (Ibid; cf. Matthew 26:53-65; John 10:33; Revelation 13:1). "Therefore, since we are receiving a kingdom which cannot be shaken, let us have grace, by which we may serve God acceptably with reverence and godly fear. for our God is a consuming fire" (Hebrews 12:28-29). "Godly fear" is "reverence to God" (Mounce. 1160). We must never treat God or His name irreverently, i.e., disrespectfully. We should treat His person and His name "with reverence and godly fear."

The most common byword I hear from people in general today is "O God!" or "O my God!" When I hear this exclamation I shudder. This is rank blasphemy. It is all we should expect from the ungodly people of the world. But such "impious and reproachful speech injurious to divine majesty" should ever soil the lips of a Christian.

You might say, Well I just say it without thinking; I don't mean anything by it. That's the point! You're taking the Lord's name in vain.

But I say to you that for every idle word men may speak, they will give account of it in the day of judgment. For by your words you will be justified, and by your words you will be condemned. (Matthew 12:36-37)