What is the great shattering discovery that John made in "By the Waters of Babylon"?

Throughout the entire story, John and all of his people
believed in all-powerful and mysterious Gods that had created, or been involved in
somehow, the "Great Burning" that had destroyed civilization and made things so unsafe
for the survivors.  They had a fear and suspicious superstition of the Gods or the Place
of the Gods; no one was allowed to go there, stories painted them as mysterious beings
that were very different from them.  They even called them Gods, placing them apart from
themselves and putting distance and strangeness between
them.

When John goes to the Place of the Gods and discovers
that "they were just men" like him and his tribe, his entire world changes.  He realizes
that they were not gods, but men, men that were no different from himself. He realized
at that moment that it was men's foolishness and selfishness that caused the great
burning that killed so many, and that they had, essentially, destroyed themselves. They
were not all-knowing or powerful, and were'nt god-like at all.  He takes this
information home and reveals it to his father, who wisely advises his son to reveal it
piece by piece to their tribe so that they can process it and use each bit with
prudence.

I hope that helped; good
luck!