Why do people lie?
People lie ultimately because they seek to protect the falsehoods they believe about themselves.
The world of lying is like totem pole. This would include half truths, concealment to retain personal comfort and casual white lies; everything that would preclude a double mind. It is like a totem pole. There is someone you put beneath you, and there is someone above you, which is the reason you put someone beneath you, as you seek to climb to be at the top. But you will not get to be at the top. For at the top resides the Father of Lies, Satan. He will not concede it to you.
The truth is the crucifix, and the Son of God is crucified on it; goodness and innocence itself revealed through the torture of our sins, and thus the truth of our sins is also revealed. The revelation of truth. The good thief was crucified beside the Son of God and he spoke the truth that was revealed and he went to paradise right after he died.