I am agnostic and talked about spirituality (I explored religion and many other kinds in my life) with one of my Ts, as well as many other people with a great variety of beliefs (or lack of beliefs). I always feel that if someone has a healthy relationship with their spirituality, they are usually tolerant of diversity and different views and do not take such discussions personally. If not, it's not for me to be uncomfortable and figure out why. If it's something you really want to discuss, I would just talk about your views, doubts, questions etc and not ask the T about theirs.