We all do our best (I should hope) to study well and do our absolute best to discern truth. It's a fundamental quest of humankind: I need to find out what is true, subscribe to it, and live that way. I study very deeply, converse widely, read voraciously, and try to be as objective as possible. Hopefully we all do that (though I think that's a bit optimistic and ideal on my part, but I've always been an optimist kind of person. Our current media and political environment is working hard to knock that right out of me, though
).
> For example you list LGBTQ as something people can differ about, but if it turns out that homosexual sex was a sin, then wouldn't preaching that it was good and right be a sin?
Many churches do preach that it is a sin, and I believe that the Bible teaches unequivocally that it is a sin. And if it's true that it's a sin (as I believe), then yes, it would be sin for preachers and churches to teach that it's good and right. We are all accountable for our thoughts and actions. If I'm wrong, I'll face the consequences of that. If someone else is wrong, they will the face the consequences.
> In Revelation, one of the churches in Asia was condemned for allowing a woman to teach that fornication was a good thing.
Yes, Revelation 2.20. She is rebuked (2.21) and called to repentance, but refused. She will be accountable to God not only for her false teaching but also for misleading others (2.22).
> God seemed to really not like that at all
God doesn't like whatever is not true, whatever doesn't lead to holiness, and whatever interferes with a person's relationship with Him.
> Fornication was something forbidden to all the gentiles in Acts 15.
Correct. Acts 15.29. But it was forbidden to Jews also. In this case it was a letter to the Gentiles, and that's why Gentiles are specifically mentioned.
> If you're opinion on LGBTQ involves promoting, supporting, or condoning fornication, I would think you'd be in for a bad time with God.
I agree with this statement also.