You're approaching the argument incorrectly. First and foremost, we're all here on this planet, that is an indisputable fact - how did we and the planet get here. Something has to be true.
Whether there is anyone, or any group out there that that has discovered the truth, either in part or whole, cannot be ascertained unless someone knows the truth in order to discredit all the other opinions.
But, man being the highest form of intellect within the material world, chances are that he's onto something. And, if we accept the spiritual dimension to his constitution, another incontrovertible fact, then we understand that there is a spiritual realm within the universe, and therefore, a source for that spirit. Man has prayed to gods from the beginning of time, and has proven his spirituality in all his actions. Therefore, the truth is not too far from all of us, guaranteeing that some have been able to perceive it to some degree or another.