'Liar' in the Bible

If we say, “We don’t have any sin,” we make Him a liar, and His word is not in us.

The one who says, “I have come to know Him,” yet doesn"t keep His commands, is a liar, and the truth is not in him.

Who is the liar, if not the one who denies that Jesus is the Messiah? This one is the antichrist: the one who denies the Father and the Son.

If anyone says, “I love God,” yet hates his brother, he is a liar. For the person who does not love his brother he has seen cannot love the God he has not seen.

(The one who believes in the Son of God has this testimony within him. The one who does not believe God has made Him a liar, because he has not believed in the testimony God has given about His Son.)