Billions of people around the world remain steadfast in their conviction for the truth of their chosen faith while remaining ignorant about virtually every other faith. They have no foundational basis for this position other than their respective holy book(s). This conviction is both disingenuous and intellectually dishonest. Most Christians have never read a page of the Qur'an and yet find no difficulty dismissing its claims. Most Muslims have never read a page from the Book of Mormon and yet find no difficulty dismissing its claims. Additionally, these billions of people will never give conscientious thought as to the arbitrary factors leading up to their chosen belief.
Here's a little elementary algebra experiment designed with religious believers in mind. For argument's sake, let's say that you (Y) were born and raised in the United States (U). You are Christian (C) and believe with 100% certainty that Jesus is the one and only true god. Our equation might look something like:
Y + U = 100C
You + United States = 100% certainty in Christianity
What would happen if we changed the variable U and replaced the United States with Saudi Arabia? Would your belief change if you were born and raised somewhere else?
Y + S = ???
You + Saudi Arabia = ?
Saudi Arabia is an Islamist state that is officially listed as 100% Muslim (M)62, so with relative certainty we can conclude that our equation would look like:
Y + S = 100M
You + Saudi Arabia = 100% certainty in Islam
Keep in mind that you are still you and you still believe with 100% certainty that your god is the one and only true god. The difference lies with the god that you are absolutely certain of. If you were born and raised in Saudi Arabia, you would most likely not worship Jesus, but Allah and his prophet Muhammad instead. A Christian who was born and raised in Saudi Arabia instead of the U.S. would be a Muslim.
What is common to all religious beliefs, regardless of the geographic location from which they spring forth, is the assertion that divine revelation has occurred between god(s) and humans. Visions and miracles are in abundant supply irrespective of the god being prayed to. Childhood indoctrination is a major component to the continuation of religious beliefs and that tactic remains the same whether someone is raised in Saudi Arabia, Israel, or the United States. Often the only piece that changes is the specific revelation delivered to man. Depending on where someone is born and raised, their belief in both the creation of man as well as the eventual capitulation of man will be molded by sociological influences. While this influence doesn't immediately warrant dismissal of the religious belief, the point behind this exercise is to highlight the strength, irrationality, and arbitrary nature of the conviction. A Hindu's conviction on religious truth can be equal to that of a Jew, Sikh, Muslim, Jain, or Christian but conviction alone isn't sufficient to make a religious belief true. The revelations man claims to have had are often contradictory which leads us to the conclusion that a person's religious conviction is more heavily influenced by the factors we've listed than by truth itself.
If we don't allow our brains to take a mental shortcut here, we'll see that something as trivial as our geographic location can completely alter our religious choice without affecting the degree to which we believe it. The mere fact that geographical and cultural factors can be such a strong influence strains the credibility of the passion with which a believer professes in their faith. If we were born in India, we would likely be Hindu. If we were born in ancient Greece, we would likely believe in Zeus. If we were born in West Africa, we might believe in the earth goddess Ala. It is nothing more than a roll of the dice that we are born into whatever culture we find ourselves, and for the vast majority of our neighbors, it's that same roll of the dice that determines their religion.