Could you get in touch with local LGBTQ+ organizations and see if they have youth group and some resources? plenty of queer people are religious, so I would try and maybe get him to meet other members of the LGBTQ+ community who happen to be religious (or not) so he starts seeing that he can be religious and also be himself?
it’s very sad he feels so much shame about himself but it’s also a very normal part of the process of accepting one’s sexuality. Most gay people have loathed being gay at some point and felt shame about it. I am a lesbian and it definitely took almost two decades to accept what I knew about me since I was maybe 3 or 4. And I still came out as bisexual first as it seemed more palatable somehow. It’s a long process and there is a lot of shame involved and I was born not that long ago but still at a time where gay people where vilified and compared to pedophiles (still very much the case for many people.)
Your poor son is probably terrified because that’s likely all he has heard about (how bad it is to be gay). I would casually start watching TV shows and movies where gay men appear and invite him to join for movie night, not in a “we know you are gay and here is a movie specifically for you kind of way” but so it’s normalized. “But I am a cheerleader” is a very fun lighthearted movie that might resonate with your son where Christian parents send their lesbian daughter to a convertion camp, it’s a comedy, very funny and very well done and show how ridiculous it is to be against love in all its shape or form and that you can’t fight against who you naturally are, nor should you.
if it helps, I hated the fact I was gay when I was little but now you couldn’t ever find something that would make me want to be straight, I love my sexuality, I love myself, I am proud of the person I am and the people I have loved and if reincarnation is a thing I hope I am gay in each and every lives. 15 is a tricky age where you want to fit in and fear bullying if someone finds out you are gay, it’s hard. Keep supporting him through it and I would say to him “we know 15 is the age where you will start questioning yourself about all kind of topics and about who you are, and what that means. We want you to know that whoever you decide to be and whoever you are we will support you, as long as it doesn’t involve hurting anyone. So if you realize you are gay, or want to become a broadway star or would like start potery classes, go for it. It’s okay to find out who you are, and I know 15 is the age where you will get a lot of opinions you didn’t ask for about your life and who you are, might become or could become, just know that for us it doesn’t matter who you are, who you love and what the future holds, you are our child and we love you and will support you through whatever the future holds for you and it’s okay to be scared just give yourself grace, you don’t have to have it all figured out and it’s okay to be lost and confused, we all have been there, and you will be okay, I promise, even on days you think you won’t, there will be a day where you will wake up and see you are and you did. Trust in you and if you believe in God trust that he made no mistake and he made you just the way he wanted you to be and that nothing you feel or think he is foreign to, he knows what’s in your mind and what’s in your heart and he wouldn’t have created this version of you if he thought you should be any different. We love you and if there is anything we can do to help make going through the teenagers years easier for you we will always be happy to hear and work through it with you.”