Is it a sin to be LGBTQ+?

I’m very intrigued by religion, mostly Christianity. I was raised Catholic, though became atheist sometime around 6th grade. Orthodoxy caught my attention, and I’ve been considering converting; however, I support the LGBTQ+ community. I have some friends and family members who are LGBTQ+. I’m familiar with it being labeled a sin and have debated with many Christians about why it is not. I know Orthodoxy is quite strict, which kind of worries me. Due to this, I have two questions (I’m curious about all perspectives and arguments, but I ask for respectful answers and comments):

1. Why is being LGBTQ+ a sin? If you believe the opposite, why is it not a sin?

2. Would I have to drop my views on the LGBTQ+ community to be Orthodox? Is there too much conflict between them?