"It has not been demonstrated that there is a God nor has it been demonstrated that there is not a God therefore it is equally true that there may or may not be a God."
This was actually said to me once – and seems a fairly standard argument that tries to sound logical while still allowing belief in the un-provable. But this is a complete fallacy that is used by theists so often in arguments that even atheists often accept it.
Just because something can not be demonstrated either way does not make the chances of one being true equal to the other. You cannot demonstrate that there unicorns or there are not unicorns. Can you say there is an equal chance that there may or may not be unicorns? Of course not. The chance of unicorns existing outside imagination is very small. Evidence is required to demonstrate anything and the evidence to demonstrate the existence of unicorns is about the same as the evidence that there is a god.
So the chances of a god existing cannot be anywhere near 50% or even higher, no matter how much some may wish it. The odds of these are not equal to a heads/tails of a coin flip. If it were true then we would all live in fear every full moon because there is a 50% chance of werewolves on the prowl.
Some might say; ’It is not about unicorns or werewolves, it is about god’. OK put god into the same logic. What has changed? What special insight, revelation, or knowledge do we have that makes one supernatural being more likely to exist than another and even having a 50% chance of existing in reality?