When we use our tongues in a way that dishonors God’s name we use His name in vain. This is when we curse and swear. It is when we say “O my God” or any such time when the Lord’s name is used in an irreverent way. Even when we are in prayer or praise to God and we continually repeat the name “Jesus” or “Father” irreverently through vain repetition, we use God’s name in vain. It is a sacred name and should be held in high esteem no matter when we invoke it. For invoking the name of God is a weighty matter and should not be taken lightly.