I find it puzzling too, Amos, but like I said...

You can be sure of one thing. They had it presented to them at the right time....by the right authority figures...and in the right way. They now take it for granted.

Sometimes people will become deeply disillusioned with their early authority figures...as often happens to teenagers in regards to their parents (and older folks in general), for example...at which point their old set of assumptions will collapse utterly, they will find a brand new set of authorities and assumptions to live by and they will adopt a new set of beliefs, usually with just as much assurance as their previous set. (and just as little solid "evidence")

This can also happen with a young political fanatic who reverses his previous stance. Mussolini, for example, started out as a passionate socialist, but ended up as the ultimate anti-socialist.

Another thing that can happen when a set of personal beliefs collapses is that a person will become bitter and deeply cynical about all forms of belief systems. He will become a professional cynic and debunker of everyone else's beliefs. Such people are not any fun to be around...because they are forever wreaking vengeance on the world in general for the destruction of their youthful sense of trust.

One finds some interesting cases of this in people who have left behind them a church...or a political belief....or a marriage.