If you read the papers and pay attention to this sort of a thing, you know that fewer people in this country are identifying with one particular religion than a decade ago. Not only that, but the number of people who identify themselves as being nonbelievers is rising. Sorry that I don't have any specific statistics handy, but go ahead and google this stuff for yourself if you don't believe me.
Anyway, I have to wonder if the Internet has something to do with all this. After all, Internet access also went up. Of course, I'm well aware that just because two things happen at the same time, that doesn't mean that one causes the other, so I can't say that with any definitiveness. Still, I have to wonder.
As for me, my transformation from being a Christian to an atheist has been a long one, and I don't really have one quick anecdote that explains how it all happened. What I do know is that before I started going online, I had already started to identify myself as being pretty much agnostic, although I probably leaned towards belief in Jesus. There were several factors that finally made me admit that I was an atheist - a big one being when I started to sit down and actually read The Bible. Another one was when some guy on BART saw me reading it, and when I talked about all the screwed up things in it, his answers were so full of doublethink and circular reasoning. (The same circular reasoning that I continue to encounter in my debates with Christians to this day.) All that said though, a really big factor was the Internet.
It probably started when I'd be dinking around on various newsgroup sites. I'd often visit forums dealing with skepticism and the paranormal. If I'm honest with myself, I was probably just looking for something that confirmed my reasons for not believing in stuff like astrology, psychics, alien abductions, etcetera. It was pretty easy to keep thinking the way I did though because the skeptics would always completely destroy the arguments of the believers. Many of those folks came off as being not being very mentally sound, and the rest employed all sorts of logical fallacies to prove their points. (Now that I think of it, I learned the concept of logical fallacies - at least, being able to identify them by name - from these forums.)
What I'd notice is that there was a bit of crossover between the skeptics and the atheists. This led me to visiting forums on Christianity and atheism. With this instance, I can honestly say that I didn't know what I'd conclude. I wanted to see who had the better arguments, as I was pretty much on the fence myself. (I can tell you one thing, I sure as heck didn't have my strong feelings regarding the evolution/creationism "debate" that I have now. I remember even thinking that the "why are there still monkeys?" argument was a good one when I first started going online!)
Ultimately though, the atheists always had the stronger arguments and were better able to appeal to reason and logic than the Christians could. Because let's face it, once you start accepting that a virgin can have a baby, you have just turned off your critical thinking. Sure, there are Christians who can think critically, but they selectively turn that part of their brains off when it comes to their faith. (At least, those who take the miracle stories literally do.) Perhaps an argument can be made for faith that shows that it's superior to using reason and logic, but I've yet to hear it.
Did the Internet make me an atheist? Hardly. It might have spread the process along, and it certainly gave me a lot of ammunition that I might not have had otherwise. Not only that, but a bit of googling has shown that others have thought about this as well. There are a lot of unfortunate atheists out there who have to hide their nonbelief from their friends and family, and the Internet is their only outlet for communicating how they feel. (Check out the Closet Atheist.)
I can also imagine that there are a lot of people out there who are being exposed to the arguments for atheism who normally wouldn't have. Ever check out Youtube? There are a lot of theist/atheist debates going on there, and from what I can tell, the atheists dominate. Shoot, I tried typing in "Jehovah's Witnesses" and some of the first results were testimonies of people who left the religion. I can imagine that there are probably some Witnesses out there who wanted to get in touch with fellow believers only to be exposed to things that they would have never heard from anybody they know.
The Internet, for all its strangeness and problems, is most powerful source of information that this world has ever seen. Sure, there are people out there who only want to read and see things that already confirm what they feel. (I've been guilty of this, but I do check out conservative blogs from time to time just to see what their side of things is. I don't always disagree with them even! I've even changed my mind about some things! Shudder!) However, the arguments for atheism are able to get out in ways that they never did before. Who knows, maybe there are some folks who have been introduced to them through some of the stuff that I wrote.
I don't think that anybody who's already firmly entrenched in a belief system is going to come away from it due to what they read online. People who are on the fence though? It's difficult to see them being wooed over by the theistic arguments. Maybe I'm wrong. I'd love to hear from a former fence-sitter who turned believer due to what he or she encountered online. If you're out there, let me know.