'Liar' in the Bible

If we say that we have not sinned [refusing to admit acts of sin], we make Him [out to be] a liar [by contradicting Him] and His word is not in us.

Whoever says, “I have come to know Him,” but does not habitually keep [focused on His precepts and obey] His commandments (teachings), is a liar, and the truth [of the divine word] is not in him.

Who is the liar but the one who denies that Jesus is the Christ (the Messiah, the Anointed)? This is the antichrist [the enemy and antagonist of Christ], the one who denies and consistently refuses to acknowledge the Father and the Son.

If anyone says, “I love God,” and hates (works against) his [Christian] brother he is a liar; for the one who does not love his brother whom he has seen, cannot love God whom he has not seen.

The one who believes in the Son of God [who adheres to, trusts in, and relies confidently on Him as Savior] has the testimony within himself [because he can speak authoritatively about Christ from his own personal experience]. The one who does not believe God [in this way] has made Him [out to be] a liar, because he has not believed in the evidence that God has given regarding His Son.