Ancient knowledge should not be confused with ancient superstitions. Knowledge is gained through experience and education, while superstition is just a way to explain something you cannot, or will not, understand. As you gain understanding the need for such explanations declines. A perfect example is lightning.
Christians always considered lightning to be a sign of God's wrath, inflicted upon sinners for their evil ways. Until Ben Franklin determined the true nature of lightning and, more importantly, developed a defense: the lightning rod.
Church leaders called the lightning rod a tool of the devil, intended to divert God's wrath. Business owners, on the other hand, realized that their buildings weren't getting struck when protected by the rods. When Church leaders realized that the town churches were being struck repeatedly while the town brothels were not they quickly changed their tunes.
Education and understanding eliminated the need for God as an excuse for being struck by lightning. Superstition feeds that obsolete need.
A Greek mathematician, Eratosthenes, calculated the diameter of the Earth around 240BC, so the ancients certainly had the knowledge and the intelligence to use that knowledge. But that does not mean that everything they believed should be taken as gospel. They were just as easy to manipulate and mislead as modern humans.
Certainly people can believe that God resides within them. There is no one who can prove them wrong. But if they cannot admit to themselves that this belief is based only on faith and not on evidence they are no better off than some ancient shepherd cowering in his field because a comet hangs in the sky. Maintain your faith if it comforts you. But don't deny reality and don't attempt to force that faith on others.