Did you not notice that I said no conversion is necessary?  But repentance from breaking God's laws is.  Mankind sinned, missed the mark, at the Fall of Man.  But God began putting a plan in place, Genesis 3:15, to redeem mankind that culminated at the Cross (John 3:16).  And it is God who is immutable.  But you are right, our soul is created in His likeness.  Sin leaves a God shaped hole in everyone and He desires to fill it up again upon repentance and acceptance of Jesus work on the Cross (Colossians 1: 18-20).  Religion has nothing to do with a need to regain a relationship with God.  Religion is what we do as people to act out our beliefs.  A simple definition of Christianity is: God reaching down to man and man responding.