This is a curious question in that one would almost never think to ask it about anything other than religious belief.
Consider what happens if I go for a drive at high speed on a dark and stormy night and decide the sign that says “Bridge
out!” is a hoax. The sincerity of my belief in a functioning bridge cannot stop
what inevitably happens next. Consider what happens when a general sends his
armies east instead of west because he believes sincerely that is the direction
the attack will come from, and instead is attacked from the west. Again, the
intensity of the general’s convictions has no bearing whatsoever on the end result.
Reality will be what reality will be, regardless of what men and women think
about it.
What the question presupposes is that God
is uniquely uncaring about how men and women approach him. That is an
assumption which cannot be defended from the Bible.