"...the definition of faith is belief without proof..."
This is false.
"...you can not choose to believe something..."
This is true and the point well-taken, though the connection between belief and volition is way complicated, and not clearly worked out. For example, your spouse commits adultery, say, and you have to change your beliefs about him or her. That process seems to involve one's volition, but in what ways is not at all clear to me.
It is important to keep in mind that guilt or innocence and the inability to choose to believe are not connected. One can be guilty of breaking a law even though one does not know the law (and, hence, could not be said to believe it). Moreover, there are a number of situations where one can be held culpable because one should have known "X" even though one did not actually know "X".
This is the essence of Augustine's argument against the detractors of the faith in his time. Augustine argued that given the philosophical belief set of the time --largely from Plato-- one should have known god existed and had certain attributes precisely because (according to Augustine) that is exactly what being a Platonist commits one to believing. To be a Platonist --actually a neo-Platonist-- is to be committed to a certain set of beliefs even if one does not know that.