John 20:21 (NIV)
Peace be with you.
This verse could be easily read as "peace within you." A man running from God can never be at peace with God or himself. Psychology and holistic healing may offer temporary relief, but the guilt that a man carries inside will torment him continually. When Cain murdered his brother Abel, he did not repent of his sin but ran from God (Genesis 4:16). Cain then settled in Nod, which in Hebrew means the "land of the wanderers or fugitives." Cain was never again at peace with God and lived a restless and guilt-ridden life.
The peace that transcends all understanding (Philippians 4:7) is not external peace but inward tranquility that comes from being right with God. A man may commit the most heinous crimes like the thief on the cross. But when he walks in repentance in God's holy light (1 John 1:7), his conscience and soul are at peace with God.