I think it is possible to choose to believe in something, as long as you can convince yourself that you're not actually doing it. We experience it every time a theist comes in here. They give us the same set of "arguments"
[1] and we systematically demolish them, only to have our arguments and evidence bounce off a ten-foot thick titanium wall of wannabelieve. It's not as if they ever have counter-arguments or evidence that ever make us say, "Well, OK, I can see why you find that compelling, but I'm not quite convinced" or think, ~Huh. They may actually have something there.~ I can come up with good arguments and evidence for UFO's or psi. I can come up with
better arguments (IMO) for skepticism about those things, but still--believe, or at least consideration of the possibility of those phenomena can be founded on evidence. Not so with Abrahamic monotheism. They've got nothing in the holster, and they know it (or find out, after they've been here awhile). Yet they still resolutely cling to belief.
This will-to-believe aspect of Abrahamic faith is evident in the way they project wannabelieve onto us ("You atheists only reject God because you wanna be free to sin!"), and the fact that unbelief/belief in some other religion is considered a
punishable crime. That only makes sense if beliefs are presumed to be a matter of choice. Otherwise, people who believe different things are
mistaken, not wicked.
On the other hand, Christians have to at least tell themselves that they believe in Christianity because it's The Truth
tm and not because they don't want to be disowned by their spouse and/or family, they like their church, "Moral, upstanding, God-fearing Christian" constitutes their sense of personal identity, they want a happy afterlife for people like them and a miserable one for all those Other People, they feel it gives their lives meaning and purpose, etc.. They have to be able to pull off the sleight-of-mind trick of convincing themselves that they have a proper belief in Christianity, while not actually expecting reality to behave as if Christianity were true, i.e., what Daniel Dennett calls "belief in belief."
Maybe it's true that you can't really choose to believe that God will heal your appendicitis if you pray hard enough, but you can choose to believe that he will "guide the hand of the surgeon" and that it's OK to go to the hospital instead of the Church elders (James 5:14-15) because, *cough*twoboatsandahelicopter*cough*.