I enjoy The Exorcist for what it is. I don't think it's funny, I think it's well made horror. That said I don't have to posture as being "macho" to say it isn't at all scary to me. It is not. It was when I was a child, as were even campy horror movies that I love now for their humor and gore. I don't believe in anything paranormal or supernatural, ergo demons even in a fantasy setting don't move me.
When I watch TE (lazy abbreviations!) I see a little girl in makeup and some well done for the time special effects.
I think people with faith and/or beliefs in some kind of higher power(s,) or barring that, even some kind of spirituality of any kind, are more prone to being scared by demonic horror movies.