Hi BPDnot,
Welcome

I commend you for staying, even if it is for your own personal religious values. I did the same and I'm very glad that I did. It's not uncommon for a T to not tell a client about a BPD diagnosis. There can be many reasons but the most popular reasons seem to be that:
1. The T believes telling them the diagnosis could cause their stability to deteriorate. It may cause the person to begin acting out with more BPD behavior. For example, my H figured out on his own he had BPD last year. He never had suicidal thoughts or threats but after reading up on BPD and seeing that SI was often one of the behavioral characteristics, he began to make these threats. OR it could cause the person to feel like there is no hope in treatment because it's not curable so they give up trying.
2. The pwBPD just isn't ready to hear it yet
3. They don't want to the pwBPD to feel like they are just a diagnosis code. The T wants to treat the whole person and putting an official label on it could cause the pwBPD to feel uncared for.
No matter what, so long as it seems like progress is being made, no matter how slow, that's what matters. At the same time, sometimes therapists just aren't trained enough to handle BPD and it may be better to get a referral to soemone that treats personality disorders or DBT therapy.
As for you, it's time to stop walking on egg shells! What would you say is the area that you walk on egg shells the most?