Is the concept of a Redeemer only taught by Paul?
No, redemption is not a Pauline-only doctrine. The Old Testament, including Job and Isaiah, looked forward to the coming Redeemer. God began preparing for that Redeemer right after Adam sinned. Paul later completes the revelation, but the concept predates him.
Les explains that the concept of a Redeemer is not Pauline. He notes that Paul puts the cap on it and the frosting on the cake, but ever since Adam sinned, God has been preparing for the coming Redeemer. The Old Testament, like Job, looked forward to that Redeemer. Les then turns to Isaiah 59:20 as prophecy of this coming Redeemer, showing it was promised long before Paul. The little boy who made, lost, and bought back his boat illustrates how God lost us when Adam sinned and prepared for redemption.