“Yes, everyone has a conscious (except, debatably sociopaths). Have you ever met or do you know of anyone who could not choose whether or not to sin? Every time?”
What difference does it make if one sins once or every time? The conscience, like nature and the law are just witnesses given by God’s providence to turn mankind to Himself. There is no salvific grace in any of them except to point one to God, who alone can rid one of the guilt of sin. Anyone can do good deeds but no good deeds can restore fellowship with God; all that they do for the unbeliever is ameliorate to some worthless degree the eternal suffering in hell. All that the conscience can do in the unbeliever is bring the terrible weight of guilt without any source of relief except through chemistry or mysticism.