I would add social pressure explicitly. This partly overlaps with tradition (including of the family) and authority, but social pressure refers to all kinds of social relations. The pressure of people's social networks in the broader sense, especially their immediate social networks (e.g., friends, coworkers, etc.), is an important factor in acquiring and sustaining beliefs that might not otherwise be acquired and sustained. A shift often occurs in people's religious beliefs in their late teens/ early twenties, along with changes in their social networks due to the transition to college/university or the workforce. New unfamiliar social networks can challenge one's beliefs; and one may find a comfort zone in familiar ones.

Social pressure is not a good reason for believing or disbelieving something.