The most compelling explanation (that I've found so far) of what religious faith is comes from biologist Richard Dawkins. His idea is that faith is a kind of virus of the mind.
Dawkins calls "faith" a virus in an analogy with biological viruses. They are both replicators in the Darwinian sense. They use the information-processing capabilities of their hosts to make copies of themselves. They use their hosts for their own purposes.
The main thing for a virus is to replicate. Doesn't that sound a lot like the middle-eastern religions? Christians, for example, send out missionairies (who are themselves infected with the "faith" virus) to infect the minds of others. Muslims want to spread their faith by any means (including war). Muslims use the threat of death to keep Muslims from abandoning their faith. This sort of thing is bad for the people, but good for the virus.
This idea is explained in detail in a chapter in Dawkins's book "The Devil's Chaplain".