Humans need to believe in something to have some sense of control in difficult times. The more confusing the situation, the great our sense of loss of control, the greater our need for understanding. The understanding that we create may be based in relatively few facts, and it may be true, or untrue. But we perceive the patterns and act based on our understanding, regardless.
This link is to a 17.49 minute long Science Friday radio program that speaks to these tendencies in humans.
For example. The researcher posits that when we lack control in our lives, we tend to believe in things in order to have a sense of understanding what is happening. That understanding in turn provides us with a sense of safety and power, because we think we understand. Whether or not we actually do. Some of the things that people are noted to believe in (at least temporarily) are conspiracy theories, astrology, baseball rituals and a man's need to beat his wife in order to have a happy marriage. It's stressful to feel that you have lost control, a "highly aversive state" as the scientist puts it. A person who feels powerless will grasp onto anything to feel better.
The most convinced believers tend to be the gurus that create followings. These believers convince by the force of their own belief. Parts of the belief system is usually meticulously logical, and they dwell philosophically within these bubbles of logic that are based on false assumptions.
But back to control. WHEN, may I ask, does a person feel more out of control than when their own body is damaged or malfunctioning? When we are ill, we are very eager to believe that something can make us better. I suggest that this survival instinct of humans, to perceive patterns and attribute meaning to them, is the basis of a great number of people's belief not just in 9/11 conspiracies and God, but also in healing modalities such as homeopathy and applied kinesiology.
If you don't know about AK, it's the method of medicine which uses the subjectively measured strength of a person's arms to determine which substance you are allergic to, or which medicine is best to treat you with. It's as substantiated as homeopathy. And it has a following that is equal in fervor if not in size.
It is certainly true that these times we live in are uncertain, unstable, and threatening. We are all looking for ways to have strength and power in our world. No wonder we grasp at anything that seems to help.
During the Great Depression it is said that Americans started buying more books on astrology.
Enough ramblings. Your comments invited, this is baby thinking that needs refinement.
Baseline belief of mine: Humans attribute causality to events that occur in temporal proximity, and are really only correlated.