I think that a lot of people were (and still are) afraid of admitting their lack of belief in a god. Christians (and those of other religions) constantly insist that all morality and meaning in life comes from religion. And hence, anyone who is without religion must therefore be an utterly amoral nihilist. In fact even the word
atheist has a kind of derogatory association with it (in The God Delusion, Richard Dawkins describes Juila Sweeney recalling in Letting Go Of God, that her mother could understand her not believing in God....but being an atheist....an atheist!?). Some atheists have even decided to create a euphemism for atheism (
"Brights") though personally I find this somewhat misguided.
So there is a great fear of "coming out" and saying that you are an atheist. And doing so will often make you come up against a lot of ignorance, resentment and prejudice (and even outright hatred in some cases). Personally I have been told to my face that I deserve to be tortured for all eternity in hell for my lack of belief (despite living an otherwise moral life) and that my life is utterly pointless and that it should make no difference to me if I were to commit suicide now rather than waiting to die of other causes. (And these were my
friends!. With friends like these......)
But the zeitgeist seems to be thankfully changing. It is starting to become more socially acceptable to be an atheist, without so many people assuming that you eat babies. And so you hear more and more people coming out and openly stating that they are atheists.
This of course has secondary effects. People seeing others stating that they are atheists, others who may be respected, or even friends, causes them to think about their own beliefs. It makes them confront the negative stereotype of atheists that they have in their heads - the bitter angry loner who resents society. It may even cause them to question their own beliefs -
"do I really believe what I claim to believe? Do I have good reason to? Or is it just because I was brought up to believe that way?"