Why is Paul's statement that Christ came into the world to save sinners not in the Old Testament?
Scripture is a progressive revelation unfolding chronologically, so Paul’s statement belongs to a later point in that unfolding. The Old Testament emphasized the coming King who would fulfill the Abrahamic covenant. Yet a parallel theme of a suffering Savior was also promised, as in Isaiah 53.
Les teaches that Paul’s words in Timothy are a faithful saying: Christ Jesus came into the world to save sinners. He explains that the Bible is a progressive revelation, everything chronologically unfolding, so the Old Testament contains no statement exactly like Paul’s. Instead its whole emphasis is that He is going to come to fulfill the Abrahamic covenant and be the King. Running parallel, however, is the theme of a suffering Savior. Isaiah 53 promised One prepared as a sheep before shearers, who suffered the chastisement of our sins. That suffering Savior was necessary, because Jesus told Nicodemus that except a man be born again, he cannot enter the kingdom; there will be no unbelievers in that kingdom.
This is a faithful saying, and worthy of all acceptation, that Christ Jesus came into the world to save sinners; of whom I am chief.