Several factors influence the acceptance of supernatural beliefs. Possibly the most important, is the transmission of beliefs of parents and teachers to children and students when they are very young. Indoctrination, a successful strategy is unlikely that religions are the result of a master plan orchestrated by a group of great people. It is more likely that religions are the result of a cumulative process, which involved large numbers of people with diverse interests, and which converged lot of beliefs, rites and customs, many of whom ended up falling into oblivion, surviving those beliefs, rituals and customs most successful (forgive the redundancy). Many non-religious factors, including political and economic factors probably influenced the success or failure of these beliefs and customs, causing the appearance or disappearance and loss or gain of power of religion. One of the most successful ways and that is almost ubiquitous in any religion, is the transmission of beliefs and religious customs parents or teachers to begin at an early age.
It is likely to accept the beliefs of our parents without question was a successful strategy for most early humans even today. Question the fact that a food is poisonous, can be quite harmful to a child. An adult who has had time to form their beliefs from their own experiences and conjectures need not be gullible, whereas a child depends on the beliefs of their parents to survive, and should therefore be gullible, has no choice . Most religions account for the indoctrination of people since birth.