A recent series on the History Channel about the world's major religions has been very interesting to me perhaps due to my age but also because I have observed the effects of religion all throughout my life and it religion has not left me with a warm feeling.
The three major religions, Judaism, Christianity and Islam all spring from the same geography, the area which is now southern Israel. The Jewish people trace their roots back to the second century B.C. and have numerous times been descimated by various other peoples and have been carried off as slaves to other lands. There is some empiricle evidence in the form of ancient writings which, more or less, confirm their experiences and validate parts of the Torah and Old Testiment; however, much of what is written has little support except for the Bible which has been edited and modified over the many centuries. While Judaism came out of a notion of polytheism (many gods), monotheism (belief in one god) was the primary belief in the later years.
These two religions coexited for a short time in the area of Palestine around and subsequent to the life of Jesus. Most of the earlier Christians were Jews.
Islam came later in the middle of the first millenium. Islam built on earlier tenets of Judaism and Christianity but did not accept Jesus as the son of God.
And so her we are, a couple of thousand years later, with numerous denominations of Judaism, Christianity and Islan. These range from an almost primitive acceptance of what is written in the Torah, Bible and Koran to more liberal accommodations.
So, unless one believes in the literal interpretation of the various holy books, the only other thing you have to hang your hat on is faith. Faith is difficult to describe as it defies logic and relies mainly on what someone else tells you that he/she has heard or experienced.
This has led to legions of evangalists from all faiths who claim to have either had a conversation with God or have experienced God's direct effect on their psyche. They all are very sincere and exhibit a built in framework on how everyone should live their lives, how they should replicate ceremonies, and such simple things as what we should include in or exclude from our dinner plates.
This naturally leads to squadrons of folks who make a living by selling this subscription from heaven to the many. If I was selling snake oil, I would expect that my customers would at least validate my research. This is not true of the rabbis, priests and imams who feel that they have the answer for everything and enjoy the many privlieges of their exhaulted status while the rest of us rabble perform the ceremonies, furnish the cash, and blindly follow the tenets, never thinking how foolish it is to expect a reward of several dozen virgins should one choose to use his/her body as the vehicle to transport death and destruction to others.
But, then, I did the same thing with a B-52 during the Vietnam difficulties. Without the reward of virgins, though.