The third commandment is “You shall not misuse the name of the Lord your God, for the Lord will not hold anyone guiltless who misuses his name” (Exodus 20:7). This means that we must not use God’s name in a wrong or inappropriate way.
Swearing
Some people use the name of God as a swear word, an exclamation of fear or surprise. This is one way that God’s name is used inappropriately. Most people who are Christians wouldn’t say or use God’s name in this way.
Moreover, we are warned: “You shall not swear by my name falsely, and so profane the name of your God: I am the Lord” (Leviticus 19:12). Jesus even says it is better not to swear by God’s name at all: “Do not take an oath at all, either by heaven, for it is the throne of God, or by the earth, for it is his footstool, or by Jerusalem, for it is the city of the great King. And do not take an oath by your head, for you cannot make one hair white or black. Let what you say be simply ‘Yes’ or ‘No’; anything more than this comes from evil.”
False prophecy
Another possibility is when people say “God says…” to add weight to what they are saying, or trying to force others to obey their words. Unfortunately this is a way that Christians sometimes misuse God’s name. Saying these words glibly, or when God has not spoken, is something that God hates. In the Old Testament He used His true prophets to speak out against the false prophets, who said that God had spoken when He had not at all. See Jeremiah 23:25, Ezekiel 22:28, and Deuteronomy 13:1-5. False prophets were to be put to death.
There are many people today who try and persuade others that God has spoken through them. If they misuse God’s name for this goal, when He has not spoken at all, God says He will not hold them blameless. For Christians, when we know, love, and honor God, it is unlikely that we will use the name of the Lord God in vain, but we need to be careful in the words we say.
God does speak to us, God may well give us a message to give to someone else. But make sure that the Holy Spirit has really put these things on your heart. Otherwise we also may find that we are taking God’s name and using it inappropriately, using it for our own ends instead of to glorify God. We should always revere His name and glorify Him.
Read more in What is the Bible?