Private or public college? what are the advantages and disadvantages?

High schoool senior here and super stressed about college! Okay so I really want to attend a private college only because of the SMALLER cl sizes. I do not want to be in a university in a lecture hall consisting of 300+ people. How do they expect you to learn with that many people? Anywho, I am not a religious person at all. All private schools have some kind of religious affiliation and I feel like they basically force you and teach you their religious aspects, which I don't like. I dont want to feel like an outsider because I don't know anything about their religion and stuff. Like are you expected to go to church everyday and pray and whatnot? I just can't see myself fitting in at a private university. I can't really see an advantage of a public university, because like I said I would prefer to have smaller cl sizes, but maybe someone can sway my opinion? please and thanks!