As a believer in Christ as Lord and Savior, my recommendation is first do your own pre-research on Christianity, Catholicism, Judaism, Islam and maybe Buddhist. Do this so you have a good idea of what they each believe. For example Christianity and Catholicism is not the same. Similarities yes but not the same. Do your research so you can make a decision in your mind about which sounds the best and most valid to you in terms of spirituality and life.
I'm saying do all that cause I'm suggesting you and him have a sit down discussion about what you believe and what he believes. Ideally the discussion should include spiritual things, but at a base level you and him should be able to have conversations and compare how ya'll believe about things like: Kids:Have children or not, things like how to handle friends individually and together as a couple. Um sex: Monogamous or open relationship to allow experimenting with other people. Goals: What are you trying to do in life and what is he trying to do in life and does that allow for you and him to be together.
Maybe a little politics too, like is Donald Trump great or is he the devil en carne, abortion:women's rights or protect the child in the womb. Basically talk about some things that really matter and see if ya'll are compatible or not. The religion thing yeah he can choose to love you despite how you choose to believe if he wants to, but that can cause problems down the line. It wouldn't be the worst thing if you saw and experienced things the way he does through the eyes of Catholicism.
As far as spirituality goes, I certainly recommend you try to nudge him towards Christianity.