Beliefs are taught perspectives of life, the world, everything. Perspectives are a way of looking at and perceiving things in a particular way.
There is the classic example of perspective, a line drawing of a set of stairs. Depending on how you look at it, you could just as easily think the stairs are leading down as leading up. There is no correct answer, both perspectives are equally valid.
But, with beliefs, a choice is made between two or more views. One view, or perspective, is labeled good and the others are labeled bad. This labeling is enforced and reenforced by the dominating culture.
Given people's propensity for conformity, for desiring to belong to the group, (however you define "group") people will adapt their personal perspectives/beliefs to that of the group.