Well... ever watched the TV-show Stargate? Just imagine it. We go travel to the stars and bumps into a civilization on the stone-age stadium. Now, will they think we're Gods? Perhaps.

That's the reason a real God can never show themselves to us, or prove themselves to us, because if they could prove themselves in the material world, would they not just be flesh and blood but far more advanced than us?

Nope. God has to be something completely different than the physical world we're living in.

Side-note

however, never underestimate the knowledge of those more advanced than yourself, and never reject this knowledge just because you may not understand it...