For what can be known about God is plain to them, because God has shown it to them. For his invisible attributes, namely, his eternal power and divine nature, have been clearly perceived, ever since the creation of the world, in the things that have been made. So they are without excuse.

But if there is no resurrection of the dead, then not even Christ has been raised.  And if Christ has not been raised, then our preaching is in vain and your faith is in vain.

But he was wounded for our transgressions; he was crushed for our iniquities; upon him was the chastisement that brought us peace, and with his stripes we are healed