Most people do not come to their beliefs by a deliberate process. They are influenced into believing things by the happenstance of their lives - what part of the world they are born in, who their parents are, the teachers they interact with, what various figures of authority, friendship, love and respect tell them. They are influenced by the course of events in their lives.
Mostly, they are guided in their beliefs by emotional attachments and through emotional events, and by the structure of whatever local society exists around them. That's not to say that they adopt the consensus beliefs around them, but rather that those local group structures serve as the grounding for however their particular belief structure assembles as time goes on, pro or con. One might rebel against their local beliefs, but then those local beliefs are still the basis for their rebellion.
And, usually, this is not a deliberate process, but rather just a happenstance collection of views that are usually not very well thought out. Which usually ends up with people committed to hypocritical, self-conflicting, unsupportable and/or even disabling views. Committed to them on a deep, emotional level where their beliefs become a large part of their sense of self. Challenge their beliefs, and you've attacked them personally.
How many people, do you suppose, are willing to set aside all that they believe (even if possible), and start with a blank slate, and pose these questions:
1) What should I believe, and why?
2) What do I want to believe?