To take the name of the Lord in vain means to use it unnecessarily, wrongfully, falsely, disrespectfully, incautiously, and irreverently.
1. Using phrases such as "Oh my God!" and "Jesus" as an interjection (or worse, as an expletive, along with words such as "shit"). Usually, it is part of a person's language, but it must be consciously removed from speech (Matt.12:35-37; Eph.5:4)
2. Saying that God had said something when He had not said it. This applies to even wrong and twisted interpretation of God's word (Eze.13:6; 22:28; Matt.15:9)
3. Swearing by God's name falsely (Lev.19:12; Matt.5:33-37)
4. Saying that they are being led by God, when actually they are being led by their own lust (James 1:13,14). For example, one may say that God was leading him to marry a girl, or to go to some place, or do this or do that when actually he is being carried away by his own desires, presumptions, feelings, and emotions.