'Liar' in the Bible

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

The one who says "I have come to know God" and yet does not keep his commandments is a liar, and the truth is not in such a person.

Who is the liar but the person who denies that Jesus is the Christ? This one is the antichrist: the person who denies the Father and the Son.

If anyone says "I love God" and yet hates his fellow Christian, he is a liar, because the one who does not love his fellow Christian whom he has seen cannot love God whom he has not seen.

(The one who believes in the Son of God has the testimony in himself; the one who does not believe God has made him a liar, because he has not believed in the testimony that God has testified concerning his Son.)