It is scary.
On the other hand (and this meant to be encouraging), when such an apostasy occurs, there is usually some glaring moral fall—i.e., something so glaring that it takes no finely-tuned “discernment” to ferret it out: an illicit affair or marriage, frequenting the bus stops or smut shops, etc. I am not speculating or attributing, just sayin’. In lives where there is no such elephant-in-the-room moral lapse, total intellectual rot is rare.
Ping to my post #49. IMO you may find your smoking gun.