Contraception is telling God that you will not serve him with your body. And when you start telling God "No, I will not serve. I will not be fruitful and multiply as you command me to in this marriage. No, I will not serve you this way, God." Ah, but you've just signed up with someone else who said he wouldn't serve and then crawled out of the garden on his belly eating the dust.
If, as you suggest, contraceptors go to hell, you're going to have plenty of room in heaven. ;)