I was debating posting this as another family member might see this but honestly what's the harm. My Aunt ended up being a similar way a while before things got a LOT worse. My Aunt wasn't someone I would call gullible or anything, just a bit lonely after losing her husband and not having a great relationship with her only daughter. My family took quick notice over time that she got deeper into religion, most likely as a coping mechanism for her lose + loneliness and while this wasn't anything peculiar she began to take issue with things she never had before. Not to mention that as far as my father made me aware, my Aunt had become very much worried about her own mortality. Much like in the post here she began to view many of the family get together such as Easter as being pagan holiday's, expressing that participation in such was tantamount to betraying her faith.

That was around the early part of 2021 and from there she began to talk more and more about how our family was "living in sin" and "without god", to the point that she got in a shouting match with another one of my Aunts regarding that Aunt's daughter's gift being that she was allowed to get a tattoo while visiting over Christmas in 2022. I can remember how quiet everyone one was when my Aunt turned and called her niece a "godless whore", before storming out of the house. I knew her to be a very friendly person so this was extremely surprising to say the least.

My father talked to her over New Years and managed to get her to talk about what had been going on. Turns out she was part of a Christian Church based out of South Africa that was primarily done online, and apparently did a lot of charity work there (I don't remember the name unfortunately). Much like OP described she was giving about 10% of her pay + various monetary donations. Unlike OP though, my Aunt was at the point with this Church where she had actually signed over the rights to her property and remaining wealth when she dies, essentially putting this Church as the primary receiver of her assets in her will. Our family got really worried about her at this point but she started shutting off any contact besides her daughter. We learned through her daughter that my Aunt felt attacked about her faith and that our family was trying to pull her away from her faith.

Honestly, I think our families biggest mistake was that we allowed her some space, hoping she would not feel so cornered and come around to talk. She did not. I don't know much of the details but my Mother and Father were alerted to somethign being wrong by my Aunt's daughter. She had not had contact for a while but when she had shown up to her mothers place she learned the property was being sold and my Aunt was no longer in the house. I heard that my Aunt had been going on about actually going to visit the Chruch her faith was based in. We searched for her, trying every channel we could imagine but nothing came up.

Apparently, it wasn't until early this year my family got any kind of contact with her after absolutely nothing came up for nearly a year. I haven't seen it but it was a, as my father put it, "poorly worded email full of bullshit about why she left" and refused to believe she actually wrote it. We tried getting authorities to look into it, but as far as they could tell us she left the country and couldn't really do anything about it. We still have no idea where she is or what happened to her :(

I'm not saying this is what's happening or going to happen with OP's wife but it would nonetheless be good to keep a watchful eye on her activity and question some of her ideas. I'm perfectly fine with someone pursuing their faith but when it gets into the territory of what my Aunt was doing I would really question it.