Originally Posted by Fuuma
It's not that there are less people in the general population who could possibly be atheists, it's that they never took the time to seriously consider the question of religion and find out it isn't part of their conception of the world.
To expand on this, as someone raised in an exceedingly Christian (evangelical) home, by my own definition and that I was raised with, far fewer Americans than currently do so can really call themselves "Christian" in any truly meaningful sense. They will tell you that they are because they have some sort of connection to the belief system, feel it's part of their heritage, celebrate a few holidays, and go to church once in a while, but they know almost nothing about what they claim to believe, and rarely think seriously about it. Had they been raised Buddhist, they'd be Buddhists; had they been raised atheists, they'd be atheist, etc. And, since we live in a nation where Christianity is basically the default, there are going to be a lot more Christians who live like this than there are going to be atheists. Most people are forced to do a lot of thinking and self-questioning before they become atheists. Similarly, a lot of truly devoted Christians are forced to do the same, but there's no easy way to separate them out from the masses of people who are just sort of Christians by default, since they're both just referred to as "Christians".