I recently spoke with a person who... it's difficult to describe. Nominally, she was an Orthodox Jew. She was also highly intelligent, conversant with some of the archaeological evidence against her religion, and the shallow standard arguments against religion that religious people know about. For example, she knew that Mordecai, Esther, Haman, and Vashti were not in the Persian historical records, but that there was a corresponding old Persian legend about the Babylonian gods Marduk and Ishtar, and the rival Elamite gods Humman and Vashti. She knows this, and she still celebrates Purim. One of those highly intelligent religious people who stew in their own contradictions for years, elaborating and tweaking, until their minds look like the inside of an M. C. Escher painting.
Most people like this will pretend that they are much too wise to talk to atheists, but she was willing to talk with me for a few hours.
As a result, I now understand at least one more thing about self-deception that I didn't explicitly understand before—namely, that you don't have to really deceive yourself so long as you believe you've deceived yourself. Call it "belief in self-deception".
When this woman was in high school, she thought she was an atheist. But she decided, at that time, that she should act as if she believed in God. And then—she told me earnestly—over time, she came to really believe in God.
So far as I can tell, she is completely wrong about that. Always throughout our conversation, she said, over and over, "I believe in God", never once, "There is a God." When I asked her why she was religious, she never once talked about the consequences of God existing, only about the consequences of believing in God. Never, "God will help me", always, "my belief in God helps me". When I put to her, "Someone who just wanted the truth and looked at our universe would not even invent God as a hypothesis," she agreed outright.
She hasn't actually deceived herself into believing that God exists or that the Jewish religion is true. Not even close, so far as I can tell.
On the other hand, I think she really does believe she has deceived herself.
So although she does not receive any benefit of believing in God—because she doesn't—she honestly believes she has deceived herself into believing in God, and so she honestly expects to receive the benefits that she associates with deceiving oneself into believing in God; and that, I suppose, ought to produce much the same placebo effect as actually believing in God.
And this may explain why she was motivated to earnestly defend the statement that she believed in God from my skeptical questioning, while never saying "Oh, and by the way, God actually does exist" or even seeming the slightest bit interested in the proposition.
This I can understand.
I am a protestant Christian and your friend's experience with "belief" are similar to mine. Or seem to be, from what I gather in your post.
One thing I've come to realize that helps to explain the disparity I feel when I talk with most other Christians is the fact that somewhere along the way my world-view took a major shift away from blind faith and landed somewhere in the vicinity of Orwellian double-think.
The double-think comes into play when you're faced with non-axiomatic concepts such as morality. I believe that there is a God - and that He has instilled a sense of right and wrong in us by which we are able to evaluate the world around us. I also believe a sense of morality has been evolutionarily programmed into us - a sense of morality that is most likely a result of the formation of meta-political coalitions in Bonobo communities a very, very long time ago.
These two beliefs are not contradictory, but the complexity lies in reconciling the two. This post is not about the details of my Escher-esque brain, so suffice to say there are questions unanswered by viewing only the scientific side and there are just as many unanswered if viewed only from the spiritual side.
Simply because your friend is not blind to contradictions in the Orthodox Jewish belief system does not mean she does not sincerely believe - or that she's deceived herself into believing that she believes. It means that she, as all intelligent believers who practice crisis of faith should, understands just how much she doesn't understand.
Do you have a list?