> I don't believe the Catholic church (or other denominations of Christianity, or Mormon church) would allow a LGBT couple to officially join.
That's not entirely true. No legitimate catholic church would prohibit lgbtq couples from joining. The more conservative ones definitely would not condone their lifestyle, however, and probably none would agree to marry them. So if you are lgbtq you should probably just give some serious thought into more liberal denominations.
I was pointing out an obvious example of a facade of "welcoming all" from the community (would not prohibit people from joining, anyone can show up and volunteer) vs. really welcoming all where anyone could be full members through all of their ceremonies like baptism, confirmation, marriage, etc. or even allowing anyone to pursue theological leadership positions like pastor, deacon, priest, etc.
That's not entirely true. No legitimate catholic church would prohibit lgbtq couples from joining. The more conservative ones definitely would not condone their lifestyle, however, and probably none would agree to marry them. So if you are lgbtq you should probably just give some serious thought into more liberal denominations.