how do I handle my previously atheist sibling suddenly becoming religious?

TW: religion

I'm ex-religious. My step-sibling was never religious. We're very close, and since they've been in their current relationship the last couple years, they've done a 180 from being completely anti religion to suddenly identifying as religious. This is especially strange to me considering they are also queer, and historically this religion is not kind to members of that community.

This sibling is neurodivergent and tends to latch onto their SO's interests when they get into a relationship, rather than maintaining their own identity. I find it concerning, but I know they're young, so I try to be understanding. Their (straight cis) partner has definitely encouraged them to pursue this path, and I know my sibling wants to be liked by the partner's family - I just worry that my sibling is doing this not for themself, but to go along with the partner and the partner's family.

I'm not sure how to handle it. My initial instinct is to crack some jokes(we tease each other a lot) or say I never expected them to go in this direction.

They once jokingly (but not so jokingly) accused me of just having religious trauma, and that's why I don't understand them wanting to pursue religion. I don't - I simply find this religion to be inherently anti-women, anti-queer, and I don't agree with a lot of what it promotes.

How do I maintain our relationship without encouraging this situation, but also without coming across as judgemental? Help 🙈