You have a few options available to you. If you both genuinely don't feel a relationship can work out and it's too painful to be around one another, the simplest answer is to cut each other out of your lives as completely as you can. You can't heal and move on if you're renewing that agony each time you see each other. I am by no means saying this is an easy route to take. It's long, it's painful, but ultimately it's the best way to move forward -- and you will move forward, even if it doesn't feel like it at times.

The other thing I want to pitch out: religion differences can be worked with in a relationship, but it's something both of you would need to diligently work together on. For reference, my boyfriend is a devout Hindu, I am not religious at all. I know his religion is a very large part of his life and very important to him, and I support that wholeheartedly. He doesn't expect me to convert, and I don't expect him to abandon his faith, and we were very up front about that from the beginning. I have attended services at the Hindu temple with him, and he's celebrated things like Halloween and Christmas with me.

You are both very young still and have your entire lives ahead of you. You can take some time apart and grow as people and see where things lead you in the future, but also don't feel that he might be the only person you'll ever fall in love with.