No, atheism has a much more efficient system for conversion...it's called public education
Efficient? Hardly.
I'd venture to say that most people don't become atheists until college, at least. The public schools are hardly churning out the atheists, if my experience is any indication. And yes, I had the same curriculum as you. For all your agonized, sweaty-palm agitation about science birthing atheists, it doesn't seem to really happen, now does it? Certainly not with the efficiency that your churches turn out believers.
in which a purely materialistic explanation
Materialism = atheism? How does that work?
If I play Monopoly, and we play it strictly "materialist", where the rules don't make any mention of God, are we playing atheist Monopoly? If I have coffee, and the label doesn't mention God as the origin of the beans, am I drinking atheist coffee?
Or isn't it at least possible that there might, just might, be situations in which the existence or qualities of your god might not be relevant?