Pilate asked Jesus, "What is truth?"
Truth can be anything you believe to be true--even if is a lie. The longer you are told a lie about the same thing continually, it eventually becomes a truth to you.
Psalms 24: 3,4 asks, "Who shall ascend the hill of the Lord? And who shall stand in His holy place? He who has clean hands and a pure heart, who does not lift up his soul to what is false and does not swear deceitfully."
Believing a lie to be the truth is lifting up your soul to what is false. People swear to the truth; in the courtroom, your right hand is laid on the Bible and you are made to swear to tell the truth. Suppose as a child, you were called a name over and over, i.e. stupid or ugly or no good--either in words or actions--how your parents treated you in relation to being stupid or lazy or any other negative word. The child starts to believe they are stupid or worthless or unloved and eventually those things become a truth they live by through life. That child has lifted his soul to what is false and was deceived by a lie. Just like Adam and Eve.
Jesus always told the truth. He told us, "I tell you the truth" many times in His teachings. His truths are different from ours and makes it difficult at times to relinquish our lies that we believe are real. So, what is truth and what are lies and why are we so reluctant to face the truth, the whole truth and nothing but the truth? Jesus also told us, "I am the Way, the TRUTH, and the Life; no man comes to the Father except through Me."
Truth in a lot of cases is hard to face but in knowing the truth, feeling the pain of it, releases us from its influence and we are truly free.