Who is the antagonist in "By the Waters of Babylon"? What is the setting?

Upon first thought, one might think that the "Forest
People" are a classic antagonist, simply because we learn that they frequently are at
war with the neighboring tribes, and even hunt individuals down.  As John is on his
journey, he is very wary about running into the Forest People, worried that they will
take him, harm him or kill him.  He even refers to them as a people that is less
advanced, and more unfortunate than members of his own tribe.  Then there are the
radiation-filled metal objects, the wild dogs, the Place of the Gods, and the Gods
themselves that are painted in ominous and dangerous
terms.

However, the Forest People and other items are not
really a main focus of the story; rather, they are more of a side-note in the main
action that occurs.  Instead, focus on the ending of the story, when John realizes at
last that the Gods were the ones responsible for destroying themselves, and that they
were just men like he is.  He realizes that "they went a dark road," turning to the
vices and crimes that eventually led to their own destruction.  Because of that, most of
mankind was destroyed.  As his father concludes at the end, they "ate knowledge too
fast," and didn't temper their technology and intellegence with wisdom and compassion;
this led to their destruction.  If you think of the story in these terms, the main
antagonist could have been men.  Themselves.  Embracing technology while leaving behind
our humanity. Then, John's tribe had a fear of the place of the Gods and the Gods
themselves; that was a factor in their lack of progression along the way, so that could
be considered an antagonistic force in their lives--ignorance and
fear.

I hope that those thoughts help a bit; good
luck!