Having faith in someone’s ability do something, such as a test as in the example you gave , is not quite the same thing as having faith in God. Your son is real and god is imaginary. You can have a good idea how well your son will do based on the evidence that he has studied hard and has the right attitude. None of this can be applied faith in either God’s existence or his ability affect anything, as there is absolutely no evidence support these assertions. I therefore see what you mean about belief in God being blind faith. I would actually call it misplaced faith.