They speak against you with malicious intent;
your enemies take your name in vain!
Notice that one of the examples that David uses to show how these people are truly the enemies of God is the fact that they are taking God's name in vain.
This is a command that we take lightly sometimes, but it was mentioned in the Ten Commandments fairly high up on the list. Mentioned before murder and adultery.
Consider today how you use God's name. Do you refer to Him in an empty, meaningless fashion?