'Liar' in the Bible

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

One who says, "I know him," and doesn't keep his commandments, is a liar, and the truth isn't in him.

Who is the liar but he who denies that Jesus is the Christ? This is the Antichrist, he who denies the Father and the Son.

If a man says, "I love God," and hates his brother, he is a liar; for he who doesn't love his brother whom he has seen, how can he love God whom he has not seen?

He who believes in the Son of God has the testimony in himself. He who doesn't believe God has made him a liar, because he has not believed in the testimony that God has given concerning his Son.