Most religions are exclusionary. You need to join, and participate and believe in a specific way. Sure, I could attend services most places (not all) and be welcomed in the door, but in most of most it wouldn't be truly acceptable for me to participate in certain aspects, i.e. communion. This is why I do not participate in any organized religion and why no religion should be a part of governmental policy. No denomination, let alone the whole group as a whole, believes in the same way and leads to greater conflict, imo.