From what I understand, the "eternal pain and suffering" is just not being near him for eternity, but that's the thing with religions usually there are 100s of different interpretations of stories that were written after thousands of years of oral tellings. "If what is said about God is true" becomes a moot point because no one agrees what he said. Who knows if not believing in a god can cause eternal pain and suffering or what that suffering entails if it exists. The story had those details once it was written down, but who knows if it was there in the original oral telling.

I personally believe that the stories are just outdated allegorical stories. Satan and the many other people punished by "god's wrath" in the beginning of the Bible are just allegorical figures for people who don't follow the virtues of the story. I mean Satan's fall from grace was because he thought he was superior to god, which is how you describe atheists that use a moral argument to justify their atheism (they'd probably be more agnostic than atheist though if they are entertaining the thought that god could exist).

If you look at the Bible as a collection of allegorical stories on how to live a good life, then it becomes clear why "god" and his rules often suck in a modern context. It is a guide to living a good life thousands of years ago, and human beings and life has become much more complex as time has gone on. We need to acknowledge and criticize how awful the bible's and other religious teachings are, so we can move on and write a new guide on how to be good people who live good lives.