IT'S NOT A CONSCIOUS CHOICE. You you either believe or you don't.
It's like when you feel attraction for a person. You either do or you don't. Some people will tell you "she's ugly", but in your mind you're attracted.
I'm going to play Devil's advocate here.....
I used to agree. But now I wonder. Because if we are saying that belief is something we have no control over, then ALL manner of belief - including racism, homophobia, misogeny, as well as positive beliefs such as patriotism for example, are also uncontrollable and we should amend our thinking accordingly (heh - except of course we CAN'T change our beliefs!).
Clearly though, as you said, beliefs CAN be formed and changed by environment. Attraction, for example, is at least partially a product of environment, one only has to compare paintings of Ruebens to today's ideal of beauty to see that, or look at different types of attraction from different countries.
Looking at racism, for example - if a racist spent a significant amount of time living and working and socialising with a bunch of great guys of another race, would his beliefs change? I'm going to say yes - not immediately, but certainly over time.
So if environment will change belief, can we say that if we deliberately change our environment, we will by doing so change our beliefs? Again, I'm going to say yes - if you want to be a more successful dieter, you stop walking past McD's on the way home, to pick one example.
And so, if all atheists decided "okay - I'm going to go to church every day, and pray, and sing, and really try to understnad this god guy", is it guaranteed that not a single one would see the light? Or would it be the case that a significant number of them would turn Christian, more than would have done so if they had NO immersed themselves in the environment, and "tried"?
Unless we want to throw away a whole load of evidence on how human beings tick, I think we have to accept that we'd see a lot of converts. Which, unfortunately, means that in many ways the believers are right - we COULD be believers, if only we'd just TRY.