Or is God simply rewarding him for correct choices and behavior? no grace , no mercy ... pay due?
Why did God give the law?
We are saved the way God says he will save us. The Bible says that many things lead to salvation, including grace, faith, repentance, confession, and baptism. They are all necessary. God's grace is not unconditional, if it was, then everyone that has ever lived would be saved, and the Bible clearly teaches that is not the truth.