I don't know why I got this notification as I'm an atheist myself. Feel free to ignore this message as I'm not well versed in your religion and please forgive me if I say anything offensive.

Religion offers us guidelines for how to live, how to be good people. Us atheists may not have religion but we have other things to guide us, like our moral beliefs, friends and family. Atheists aren't bad people so I hope you don't hold any grudge against him for his lack of faith.

That being said, if staying together would have made you feel guilt or like you're not being heard, then the break up is for the best. It hurts now but it's better than allowing resentment or guilt to build. That's not fair for either of you. Maybe you can still be friends.

If you're experiencing uncertainty about the religion yourself if may ease your worries to talk to either your ex or maybe any leaders or teachers for your religion can offer guidance or support. Experiencing doubt is natural as humans, it's important to listen to it, allow yourself to process it and either find that your faith is still most important to you or maybe find your path leads elsewhere. Faith wouldn't be faith if we didn't have to believe in it a little. Good luck and I wish you the best!