1 Corinthians 15:17
“And if Christ has not been raised, your faith is vain.”
With whatever is clear and confessed, he keeps on surrounding the resurrection of Christ, by means of the stronger point making even that which seems to be weak and doubtful, strong and clear.
“You are yet in your sins.” For if He was not raised, neither did He die; and if He died not, neither did He take away sin: His death being the taking away of sin. “For behold,” says one, “the Lamb of God, which takes away the sin of the world.” But how “takes away?” By His death. Wherefore also he called him a Lamb, as one slain. But if He rose not again, neither was He slain: and if He was not slain, neither was sin taken away: and if it was not taken away, you are in it: and if you are in it, we have preached in vain: and if we have preached in vain, you have believed in vain that you were reconciled. And besides, death remains immortal, if He did not arise. For if He too was holden of death and loosed not its pains, how released He all others, being as yet Himself holden of it? Wherefore also he adds,
Source: Homilies on First Corinthians (New Advent)