How can a belief become a deeply held one if you do not question every aspect of it?

Do you often question your own beliefs?

If so, why? If not, why not?

For me, I find it odd that many people do not question their own beliefs frequently.

I understand the notion of people having faith (I don’t mean only in religious/spiritual form…but political, societal, etc.). However, I do not understand why they choose to simply have faith in something, without questioning every aspect of it first.

This idea stems from a thread I read last week…on some random website. For the life of me, I can not remember which it was.