'Liar' in the Bible

If we say that we have not sinned, we make him a liar, and his word is not in us.

He that says, I know him, and does not keep his commandments, is a liar, and the truth is not in him;

Who is the liar but he who denies that Jesus is the Christ? He is the antichrist who denies the Father and the Son.

If any one say, I love God, and hate his brother, he is a liar: for he that loves not his brother whom he has seen, how can he love God whom he has not seen?

He that believes on the Son of God has the witness in himself; he that does not believe God has made him a liar, because he has not believed in the witness which God has witnessed concerning his Son.