1 Corinthians 15:17:

And if Christ be not raised, your faith is vain; ye are yet in your sins.

See also:

What Galatians 2:20 Really Means
What Happened Between the Cross and the Throne?
Objection: Jesus Was Not Really PUNISHED for Our Sins; He Just Shed Blood to Atone for Them
Objection: Faith Preachers Are Trinity-Denying Heretics Because They Teach That Jesus Died Spiritually