One who says, "I know him," and doesn't keep his commandments, is a liar, and the truth isn't in him.
is a liar, and the truth is not in him: This direct statement is a grave charge. It does not mean that this person just lies: he is a liar. He is consciously a deliberate liar who habitually engages in falsehood. Further, "the truth," or God’s word (John 17:17), does not reside in him. His actions are not directed by the mandates of the word. Anyone who resists obedience to the commandments of God is indisputably presumptuous to say that he knows the Lord. He is a confirmed liar and devoid of God’s truth.