We cab choose to believe or not but only 'God' can prove his own existence to humans. So the amount of debate about whether he exists, proves that either:
He does not have the ability to prove his existence.
He does not exist outside of believers minds.
He has decided that humans are not worth proving his existence to.
He prefers to keep us guessing because he's shy.
There are other possibilities but in his continued absence we can only surmise.