understanding my fiance

I have been reading information from various websites and happily stumbled upon yours. I have been with a wonderful man for some time now. While we were dating he told me about his childhood and an organization he was apart of. I had some questions, but he was very hesitant to talk much about it.

I do know that he was a part of the COG from birth until his mid-teens. I know that when his family left the group they were ostracised, but continued to hold to the ideals of the group and believe in the principles. (they left to educate their children). And I know that this ostracization hurt him since he often talks about having no friends growing up, nor having any now.

Beyond this I do not know too much. He insists that there was never any abuse. But every now and then he comments on how he was the black sheep and always told how terrible a child he was.

I am seeing many patterns in him that I am now wondering if associated with his upbringing and if so, how can I best be an encouragement to him. He does not easily trust people and therefore finds it very difficult to make friends. He is often hostile toward new people and it is hard for him to truly believe that someone does love him. He has also been prone to fits of depression, anger and feelings of very low self-worth. We are seeking God together on this, but I question that maybe some of the root of these feelings do not lie in abuse (not sexual, but otherwise) that he refuses to admit to from his childhood.

Finally, his family, while no longer a part of the group, still very much holds to the ideals. They are wonderful people and have beautifully kind and warm children. They have been openly loving to me as a person, but have at times made it very clear that perhaps I am not the best choice as a partner for their son having grown up in Western society and lived in a church community for some time. I am finding some difficulty understanding all of this since my greatest desire in life is to serve the Lord and they have stated the same.
(I know that many of you posting on this site no longer believe in God or seek the Lord. My post in by no means an attempt to seek your conversion, but rather to seek understanding about my fiance's upbringing)