'Liar' in the Bible

if we may say -- 'we have not sinned,' a liar we make Him, and His word is not in us.

he who is saying, 'I have known him,' and his command is not keeping, a liar he is, and in him the truth is not;

Who is the liar, except he who is denying that Jesus is the Christ? this one is the antichrist who is denying the Father and the Son;

if any one may say -- 'I love God,' and his brother he may hate, a liar he is; for he who is not loving his brother whom he hath seen, God -- whom he hath not seen -- how is he able to love?

He who is believing in the Son of God, hath the testimony in himself; he who is not believing God, a liar hath made Him, because he hath not believed in the testimony that God hath testified concerning His Son;