Have you tried to believe in God?
For some atheists, yes. Others, no.
What tends to be important to a skeptical atheist is to be convinced by sufficient evidence. A specific belief isn't the goal, so much as making sure that what we believe is actually true.
When an atheist says that he/she just can't believe in a God, for whatever reason, the problem isn't that he/she isn't trying hard enough to believe. The problem is that the god claim is not supported by convincing evidence. That's what should be addressed.
Belief, for the most part, is on auto-pilot, and is not subject to the will. Without drugs, or some kind of mental manipulation, one cannot simply decide to believe that gravity doesn't apply to one's self... and then try to fly off a roof. You can pretend to believe, but you will ultimately stop yourself.
Often, atheists are told that they'll get all the evidence they want after they accept Jesus, but it does't work that way with us. We require evidence before we can be convinced, and therefore can believe.
It's like a car that needs gasoline in the tank before it can be started. Insisting that gasoline will form in the empty tank, after we start the engine, does nothing, because the gasoline needs to be present before, in order to start. That's just physics.
It's not a question of paperwork or technicalities. It's not that we need evidence to fill out the forms properly, else we'll get fired, and you're asking us to waive that for you just this once. Without sufficient evidence, we are simply incapable of being convinced, and thus believe. We couldn't do it even if we wanted to.