I'll parrot what I said on the other thread:
Technology has created an international community where many people in the world can communicate with someone in another city, another state, another part of the world instantaneously at any time, and I think that's one of the biggest threats to organized religion in history, for a variety of reasons. Religious services are no longer required to feel like you're part of something larger than yourself. A great deal of knowledge is shared freely; there's much more of an opportunity to encounter other cultures or beliefs and humanity as a whole is more educated than ever before. And I think entertainment is something now that it hasn't been in the past, television and movies and music - there's so many things to occupy a person's time. Just a few things which I think could be detrimental to organized religion.
Beyond that, I'm not sure atheism is any more 'en vogue' now that it ever has been, although I do think the idea that it's hard to see good in the world may be a part of all this. Then again, I would think that people would migrate toward religion as a result of that underlying dissatisfaction and fear, rather than away from it.