Most people have the religious beliefs into which they were born. Most Christians grew up in Christian cultures, most Muslims grew up in Islamic cultures, most Buddhists into Buddhist cultures, etc. Conversion from one faith to another happens but it is extraordinarily rare. If you give your race, gender, cultural background, the level of education, etc. to a knowledgeable statistician, then she can predict your religious views (and how fervently you hold them) with a high degree of accuracy.
This has led to an influential argument for atheism: You are a sincere Christian believer. But if you had been born in India, then you would have been a Hindu. You would have held your Hinduism as firmly as you now hold your Christianity (with a high degree of probability.) The likelihood that you would be a Christian is extraordinarily low. Thus, you should be deeply skeptical of your Christian beliefs. Just as the Hindu should be skeptical of her beliefs. The most likely explanation for all of this is that these religions are a cultural phenomenon and are basically all equally wrong. Reflecting on this fact should lead you eventually to atheistic naturalism.
This argument seems compelling to many people. But there is a serious flaw here. It is the same flaw that occurs in the argument from religious pluralism to universalism examined in an earlier post the atheistic naturalist wrongly excludes himself. If the atheist were born in India, he too would very likely be a Hindu. He would hold his Hinduism as passionately as he now holds his atheistic naturalism. It is extraordinarily implausible that he would be an atheistic naturalist. So if this fact should cause the Christian to doubt his views, then it should likewise cause the atheistic naturalist to doubt his. Thus, this kind of argument cannot be used in favor of atheistic naturalism.
What should we take away from this argument? The fact that your beliefs (whatever they are) are largely predictable in advance based on your socio-economic background is disturbing. It suggests that we are often not forming our beliefs on the basis of good reasons. None of us. Be careful to avoid the temptation to use this conclusion as an argument against opposing views, but exempting yourself.
From all of this we ought to conclude, I think, that knowing the truth is hard. That we all need to be humble about our own views. That very few things can be known with certainty (or anything approaching certainty.) That we ought to read widely and try to see ourselves as others see us. These conclusions, I think, hold for everyone including, of course, atheistic naturalists.