I say Catholic or Roman Catholic because in USA, “Christian” usually is taken to mean something like fundamentalist or evangelical or Baptist or something, and also if the person you’re talking to is one of those, they may not consider Catholics to be “Christians”.
I usually don’t talk about religion with people though, unless they ask a question or bring it up first. In the past I started long open discussions on some forums frequented by good friends of mine, just to talk generally about religion because it was interesting to me (didn’t have to be just about Catholic, any religion was okay to discuss). The discussions kind of devolved into a few people with an extreme dislike for religion doing a lot of church-bashing and just expressing their anger and unbelief generally. I understand in most cases how these people ended up thinking like they do; some of them were raised in very oppressive religious climates and had to deal with a lot of judgment and bias being inflicted on them by people that were often less educated or less responsible than themselves. But I get tired of hearing the bashing nonetheless. I also notice that when someone’s life is going badly, a lot of them find a pet peeve to whine about on the Internet all day, whethe it’s Trump or religion…the minute they get a better job or a new boyfriend, all of a sudden they’re too happy and busy to complain.