The "belief" mechanism of the human brain is designed to allow us to make fast decisions, instinctually. When we see a Lion in the wild, we believe it will kill us, and so we act accordingly. When we see fire, we believe it will burn us, and so we don't jump in to it. Areas of the brains neuron network which contain "beliefs" are protected from change, and lose their neuroplasticity, or ability to learn. For instinctual "beliefs", where quick responses are required for survival, this is beneficial.
At some point, intelligent humans learned that they could control the others by programming this instinctual belief system. This is done by convincing the subject of a fear, whether tangible, or imaginary, and then convincing them of the appropriate response. Once programmed, this part of the brain naturally protects itself from change.
This is how the humans have been controlled, first by religions, and with the same exact tactic today, by the television news.