That sounds like a cult. Anyone who seeks to isolate you from friends and family like that is trying to get you into their circle. Before I became a Christian I dabbled with the cultist Moonies. They were nice, but they kept trying to get me to go one of their retreats even when I wasn't interested. I went to one of their conferences and it just felt really 'off.' I stopped attending the meetings and shortly after, was invited to a church by a classmate at my community college.
I have friends in all branches of orthodox Christianity, from Catholicism to Greek Orthodox and pretty much every other group that has a forum on this site. None of them advocate for a total separation from friends and family. In fact, we all as Christians should encourage those around us to share their testimony and not isolate themselves.
Does this group elevate their teaching over the bible? The group I was in called themselves Christians, but the so-called study time was just reading their leader's old speeches. The Mormons have their own book which adds on teaching to the scriptures = not Christian. In a greater sense, the Muslims say the Bible is broken and their book falsely claims to fix it. The Bible is the same today as it was when it was written. There is no need for any other teaching.
