I think it is important to consider that religiosity, similar to human sexuality, is a function of two variables – genetics and religious environment. I have a theory regarding a human genetic “potential” for accepting the god concept, which in turn drives religiosity. In my theory, we are born with a uniquely set potential for belief in a god concept that I will refer to as DPL (Divine Potential Limit). My guess is that this genetically determined potential is separate from whatever potential we may have for other non-god related forms of mysticism - since it wouldn’t be impossible for an individual to believe in ghosts but not believe in god – but I suspect that they are closely related. My theory predicts that DPL governs how much influence a religious environment can ultimately have on an individual with respect to a sincere belief in god, and sincerely embracing religion. This is not a scientific study, it’s just a personal opinion based on my own observations. Consider the following distribution – with less emphasis on the actual numbers than the parameters they serve:
Zero DPL allows for zero influence from the environment. A 1-15% DPL may allow for the environment to influence towards a pantheistic limitation. A 15-35% DPL may allow for the environment to influence towards agnosticism or deism limitation. A 35-75% DPL may allow for the environment to influence towards mainstream religion limited to an allegorical context. A 75-90% DPL may allow for the environment to influence towards mainstream religion towards a varying literal context. A 90-100% DPL may allow for the environment to influence towards a fundamentalist or evangelical mindset. Keep in mind that not everyone reaches their unique DPL, since not everyone is subject to the same religious environmental exposure. Without doubt, there are agnostics who have the potential to rise higher in the distribution.
Having high DPL also does not mean that you are incapable of having no belief in god, as demonstrated by the high percentage of atheists who were formally theistic. There are also devoutly religious people who claim they were once atheist, although my personal experience has indicated that the reverse of this occurs far more often. Some people, myself included, have had significant enough exposure to religious environment to realize that our DPL is most certainly zero, and that our atheism will never change unless a god shows up in person to change it for us. Please note, that does not make us agnostic – it just means we are not so stubborn as to deny something that would happen before our very eyes. I would just as easily believe in flying unicorns if a pack of them were to land on my lawn in front of me.
The intensity of a religious environment can obviously change dramatically with location, culture, family, education, advertising, etc. It’s hard to say how an individual might develop in the total absence of a religious environment, because that is virtually impossible to experience in the modern world. However, thousands of religions have started by themselves throughout the history of humanity, so it stands to reason that those with higher DPL invented these religions, probably to explain the things that they had no ability to understand about nature. It could even be posited that this potential might have actually become enhanced as part of human evolution. If you don’t have access to the knowledge that dictates what lightning is, or how to create fire, or why water falls from the sky, or what those twinkly things in the night sky are, or why women get pregnant - then life is going to be more anxious than it would be if you made up reasons and convinced yourself to the point of sincere belief. Natural selection probably favored those who were less anxious. Just imagine, evolution guided us down of path of false understanding, but as a species we eventually grew to understand the truth about the mysteries of nature, and now we are still stuck with the biggest mystery of all, alongside a variable genetic predisposition to accept false understanding as truth. Three steps forward, two steps back. We are in the process of an evolutionary iteration that I believe will ultimately result in a species that has learned to be good without god. Either that or we are on the verge of an iteration destined to be truncated by religiously motivated mass annihilation.
In the US, freedom of religion is the law of the land, regardless of the fact that clearly discriminatory attitudes still exist between many of their adherents, and between adherents and nonbelievers. Applying the DPL theory to the population of countries where freedom of religion is not the law of the land, and assuming that as humans we all share a similar random genetic distribution of DPL regardless of ethnicity, then it becomes apparent that there must be a great many people throughout the world who are being forced to live a lie just to stay alive. In strict Islamist cultures children are branded Muslim from birth, and apostasy is punishable by death. Religious zealots in these environments would like nothing better than to execute all nonbelievers, not understanding that they will only be replaced in accordance with the laws of nature. Similarly, for religious reasons many throughout the world advocate for the execution of homosexuals. They will just be replaced in the future by the same forces of nature. This is all so incredibly unnecessary and barbaric. We are better than this.