Most people in the world already believe in some kind of God.... the problem is that in your hypothesis, God would have to get off the canvas as a separate sentient being and DO something to change things. That is not what God is. The truth is that the God above God, the Absolute, exists in everything. God is not a he. God is both positive and negative, male and female.
Atoms are not particles, they are waves of energy, all having God consciousness, and they all interconnected. It's like all matter is plugged into God in order to exist. Try plugging something in without either the positive or negative leg of the plug. What will happen? Nothing. Just as you need male and female to produce life, you need both to produce physical matter.
God is the canvas upon which everything is painted. If he ceases to exist, so does everything else. And the bottom line is, even a dumb dubbie knows this. So God is already proven to be true, it's that different people have different titles or names for God. And considering what I just described, if God wants to get something done, God has to do it THROUGH the Created.
~PS