Paul is saying if there's no resurrection then Jesus wasn't resurrected, his teachings weren't true, there's no ransom sacrifice and therefore no resurrection for us. He says in verse 32 if there's no resurrection let us eat, drink and be merry for tomorrow we die.
This is the crux of the matter, no pun intended. If Christianity isn't true then why all the slaving away, following beliefs that do not give you eternal life.
All that time and millions of dollars wasted appeasing a deity who isn't there to persuade him to give us eternal life. I've seen the inside of the Vatican! How about working so that everyone can eat, drink clean water and be happy? Then we can in good conscience enjoy our own lives, our own food and raise a glass with friends. We can stop worrying about death and let eternity take care of itself.