'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 saith, I know him, and keepeth not his commandments, is a liar, and the truth is not in him;

Who is the liar but he that denieth that Jesus is the Christ? This is the antichrist, even he that denieth the Father and the Son.

If a man say, I love God, and hateth his brother, he is a liar: for he that loveth not his brother whom he hath seen, cannot love God whom he hath not seen.

He that believeth on the Son of God hath the witness in him: he that believeth not God hath made him a liar; because he hath not believed in the witness that God hath borne concerning his Son.