If sin is real then salvation has become your bitter enemy, for salvation requires pain and suffering and sacrifice to atone for sin. But there is a problem with that. Who welcomes pain or suffering or sacrifice? No one. So who then would seek God through salvation if sin were real? No one. Therefore one of two conclusions arise: 1) God has failed to save us, or 2) sin is not real.
But how could sin not be real? Answer that question and you’ve found your salvation.