Okay, I come from a rather conservative country when it comes to religion and customs, but I think being a
LGBT is no sin at all. I don't believe in God, and I don't really like The Bible's contents even for a single bit. The Old and New Testament are both written during old times, and some "moral values" it contains taught by Yahweh to its followers are plain controversial in my opinion. Time goes on, and the world keeps changing together with civilization.
Sin itself is an abstract concept, so it's uncertain. Considering the state of the world we're currently living in, whichever is real or not remains mystery.