I totally understand that some people are religious and that they find strength in their faith. That's great if it helps them to understand themselves and their mental health. BUT it is never a valid reason to detransition. A belief in gender identity as a truth was the foundation that led to transition in the first place. Anyone who regrets their transition and wants to detransition should be doing so because they now understand themselves better than they did, not because they have replaced one belief's tenets with those of another.
No one comes to understand themselves outside of a "belief system" that delineates the nature of reality, and of the human person. Even atheists and feminists.
People taken in by gender ideology sometimes re vulnerable in part because they don't have a robust sense of these things, a systematic understanding of what is real and how we understand and relate to that.
It's not surprising that realizing that what they have is just a kind of philosophical void would send them looking for something else. Of the developed thought systems out there, Catholicism has one of the more long standing ones, with all kinds of written content from the very simple to very high level thinking.
And it has the advantage that is also addresses things like meaning and psychology and spiritual pain which also need explanations and remedies, especially for someone like a detransitioner. (or an addict.)
People come to understand themselves in part in terms of the lens they have around what it is to be human, no one does it without a lens at all.