Truth IS Truth and cannot be changed by your belief in it as truth or your lack of belief in it as truth. Your belief only changes how you act based on that truth.

For instance scientists believed that the earth was flat, although God in His Word told them it was a sphere; but because they believed it to be flat, they acted on that belief with certain behaviors and fears. Later the truth was discovered and behavior changed for those that believed the truth and did not change for those who refused to believe the truth.

How about the scientists who believed that the sun revolved around the earth and yet what was the truth? Just because you believe a thing to be true does not make it true; but your belief will change your behavior. Even in the same way you believing a thing not to be true will not change the truth, only your behavior.

Therefore, God says let every human be found a liar but I cannot lie, for I Am Truth! When God says it, it is true whether we believe it or not.  Truth is as Eternal as God is and Truth cannot and does not change!

Rom 1: 20 “For the invisible things of him from the creation of the world are clearly seen, being understood by the things that are made, even his eternal power and Godhead; so that they are without excuse: 21 Because that, when they knew God, they glorified him not as God, neither were thankful; but became vain in their imaginations, and their foolish heart was darkened. 22 Professing themselves to be wise, they became fools, 23 And changed the glory of the uncorruptible God into an image made like to corruptible man, and to birds, and fourfooted beasts, and creeping things.  25 Who changed the truth of God into a lie, and worshipped and served the creature more than the Creator, who is blessed for ever. Amen.” KJV

Repentance is humanity changing its mind to agree with God that results in a change of behavior due to a change of belief, which is true faith.