Some very interesting demographic research sheds light on the relative levels of religious belief by age and country. I'm referring to this article:
Religious Decline in U.S. Follows Europe By MATT CHERRY from HumanistNetworkNews.org Jan. 24, 2007
It reports that the USA is one of the most religious countries, with a majority of believers, and the UK is one of the least, with a minority. Each generation locks in the prevailing level of belief, younger generations believe less, so that there is a strong age related correlation, but there are relatively few individual conversions.
This is a welcome trend, it will take a long time for the believers to collectively discover that there is no "afterlife", but the voting population is swinging towards atheism and there will come a time when strong religious beliefs are an electoral liability in the USA, as I think they have already become in the UK.
People form the beliefs they will hold for their lifetime while they are young, I suspect the early teenage years are the most formative ones, where received wisdom is questioned. With the strong rise of Internet culture in this age group, I'm hopeful that the sheer breadth of opinion and information available will force the formation of less dogmatic, more flexible and more rational belief systems in the coming generations.