'Liar' in the Bible

If we say that 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 him," and does not keep his commandments is a liar, and the truth is not in this person.

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

If anyone says, "I love God," and hates his brother, he is a liar, for the one who does not love his brother whom he has seen is not able to 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.)