Am I overreacting?

Hi guys, so this is actually a first for me but I couldn't help but ask for some opinions since I dont know what to believe. I have been dating this guy for almost 2 years and he is lovely and we have a great relationship. We talk about the future a lot and we want to get married and have children. He has had a hard life and has a history of depression even get medicated for his bipolar disorder. We had a lowkey argument earlier that was not the first time though. I am a spiritual and religious person. I am positive and full of love and light. And I told him I would like to talk to our children about god and stuff. Nothing too crazy but about the good stuff. And he got all stuffed up saying that he wont lie to our kids like that and making them believe to a god that does not exists is cruel. After a bit of talking I said you can have your own opinion and I can have my own. But we shouldn't defy or belittle each other in front of the kids. He kept saying that he wont lie to them and tell them god is cruel and if he does exist he is bad for causing so much misfortune to the world. So I thought okay maybe I should lighten up the mood right? So I started talking about santa clause and the tooth fairy for fun cause it causes no harm to keep the magic alive. He refused saying that he will straight up tell them that santa claus alao doesn't exist and he is made up by coca cola and that he doesn't want our children to be morons so he will tell them straight up the truth about everything. He tends to overreact sometimes and say things he does not mean. I told him that I believe he's is gonna be the silly kind of dad who will do anything for his children to be happy and that alao intales dressing up as the Easter bunny for them. He had this negative mood and kept on interrupting me like I had just killed his family. He has a strong sense about the truth and justice but cmon...it doesnt hurt to make children believe in magic. I think ita beautiful. So before I started getting worked up I said I am mad rn, what you are saying makes me NOT to want to have kids with you and im hanging up. So I did. I am confused and I dont know what to believe. Something tells me he doesnt mean anything of what he says but I dont wanna continue this relationship with someone who is literally the grinch. Am I overreacting?