How faith works

Can people who are religious make a conscious, deliberate decision to believe in something, and then they believe in it? I don't mean organizing one's life or basing one's actions or choices on what one believes in, I mean the actual act of believing.

I'm wondering this because I occasionally see things coming from religious people who seem to think that atheists are beligerently not believing in god out of stubbornness, like a toddler holding their breath. This seems strange to me, because I, personally, cannot just believe in something. Either I believe in it or I don't, like either I like a food or I don't - it can't be turned on and off at will or changed through a deliberate decision. I did make a deliberate decision to live as an atheist rather than submitting to the hypocrisy of false piety, but what I actually believe has always remained the same, no matter how much I tried to change it to conform.

But then I remembered that my catechism also presented faith as someone one could control. Be good, don't tell lies, have faith. I can make a conscious choice not to lie, cheat or steal, say "No, I will not do that because I have decided that I am going to lie, cheat or steal," and then end up not lying, cheating or stealing. However, if I make a conscious decision to believe in something, the closest I can come to succeeding is going through the motions of believing in it. I might be able to convince the entire world that I believe, but no matter how hard I try I will not end up actually believing.

But why would they present faith as a deliberate choice if it is not? Are there people out there who can tell themselves, "From now on, I will believe that the universe is ruled by a flying red dog," and then they just automatically believe it?

If there are people whose minds work this way, I wonder if it can show up in a brain scan - could you scan someone's brain and see if they're religious or an atheist?