I have an honest question for you, Martin.
Do you really think that if no atheists existed in the world, you would be an atheist?
I can't really consider this question seriously, because it's not a possible reality. What you are suggesting is a world where every single person believes in religion and that's just not possible in practice. (Strictly speaking not likely, but practically speaking not possible.) If you ask every living person on earth you will not find a single thing everyone agrees on. The most promising question might be "do you believe that you are alive", but if you include people who are hospitalized for mental illness, there are bound to be some who will refute even that.
Now, I don't say that just to be picky. Answer coming later.
I agree with the psychological factor of being influenced by people, but it would then apply to all groups, religious, non-religious, political, sports, etc..
Yes, it does apply to everything. Just look at this forum, by being in here people see the passion and commitment other fans have to the cause and it deepens their feelings about Juve. And then they express their feelings and so it goes in circles.
We are greatly influenced by certain people, not all kinds of people, in society. I believe there are a certain type of people that possess an innate skill to be able to influence other people's actions and opinions.
Certainly. People specialize in "being influential" by picking certain careers. Politicians, lawyers, advertisers, missionaries, clerics perhaps.
I also believe that certain atheistic authors and philosophers are the prime reason for why atheists exist. They have the ability to influence other people's opinions and it is no different in theism.
I think this is an absurd statement. Like I said above, there is no possible world where everyone believes the same thing. Humans are not robots, they differ. Whenever it was that religion was first proposed, there were people who didn't fall for it. Didn't believe the prophets, didn't buy into it, for whatever reasons they had.
Atheists authors did not create atheism (of course this is a self contradiction, how could they have created something that they already were a part of?), but they can help spread atheism, which I think they are doing just now. To what level of success I have no idea.
But now, to answer the question you're driving at. Are atheists prone to crowd psychology and do they cause other people (who come into contact with them) to become atheists, not necessarily because those others have thought deeply about the issue but just because "there seems to be something to it".
The answer is: certainly.
However, I would argue that atheism is far less corrupt in this regard. Atheists don't have organizations, they don't have rituals, they don't have rules by which to live your life. In other words, atheism is not spread in any way similar to how religion is spread. When atheist couples have children they do not take them to an "atheist baptism", then to an "atheist first communion" and so on. And they do not call their kids "atheists". Weddings don't happen in the Temple of Atheism, there are not special atheist meals, it just doesn't have any kind of cultural content similar to that of religion.
So in that sense atheism is not trying to get into people conscience "the back door", that is by cultural means, rather the only way it can is through rationality. Incidentally, rationality is religion's weakest link, I have been exposed to Catholicism for 15 years and I have never been sold any kind of rational foundations for religion.
So, in conclusion. Is someone more likely to leave his faith if he has heard about atheism, know that there are other people who don't believe and so on? Absolutely.
But this does in no way negate the fact that some percentage of people never believe the story of religion in the first place, so they never leave atheism for religion. And I'm one of them. Incidentally, I only started reading books on atheism after I had clarified my position on the subject. I did not use the books to persuade me.