Liars are children of the devil and like their father do not believe the truth.
Why do you not understand what I am saying? It is because you cannot listen to My word. You are of your father the devil, and you want to do the desires of your father. He was a murderer from the beginning and does not stand in the truth because there is no truth in him. Whenever he tells a lie, he speaks from his own nature, because he is a liar and the father of lies. But because I say the truth, you do not believe Me.” (John 8:43-45 NASB)
Cannot be clearer than that. Jesus told the truth, and He was not believed because it was the truth. Liars, like Satan, operate out of their own fallen nature. Being truthful is God’s nature imparted to those who would repent and believe.
“By this we know that we have come to know Him, if we keep His commandments. The one who says, “I have come to know Him,” and does not keep His commandments, is a liar, and the truth is not in him; but whoever follows His word, in him the love of God has truly been perfected. By this we know that we are in Him:” (1 John 2:3-5 NASB)