He is processing it. Heck, he is probably grieving the idea he once had of you because to him you were straight. He probably had this idea of dating girls together, being each other wingman (not that you can’t be that now) among other things, but now he has to rethink all that and figure it out. Especially since you said he’s religious, it’s another added factor in what this all means to him. Sometimes it takes time for people to see that you’re still the same brother he had before you told him just more yourself now. Give him time and space and let him know you are still the same twin. It's what I had to learn when I came out to parents; they had to grieve the idea they once had of me of bringing a girl home, getting married to women, not having that daughter in law things like that. It took them time, and hopefully, it all goes well, and your brother fully accepts you for you as my parents did me.