At the end of Part 1, we took it as a self-evident axiom that the Universe is such that we are free to live our lives without reference (or deference) to any concept of God, gods, or divinity. In practice this means that if God exists, God refrains from jumping in to fix the Universe every time it functions in some way that causes us suffering. It means that we are on our own, except possibly for events so rare that the vast majority of us remain free to live without God nearly all our lives. Miracles may happen, but not so often that many of us can count on them.
This would be a mess if the Universe were random and unpredictable. An animal presented with aversive stimuli at random intervals, independently of its own behavior, soon cowers in its cage, suffering from what Seligman called "learned helplessness." Fortunately, the Universe is predictable in the following sense: it is self-consistent. Another name for self-consistency is the law of cause and effect.
Self-consistency has a positive side. It allows the Universe to function according to rules that we have been able to discover and to use to our benefit. We have developed agriculture, heating and air conditioning, cures to diseases, antiseptics and anesthetics for surgery, and so on. We have grown in autonomy and power as we have grown in scientific and technological knowledge. Consequently, we have grown in our average material well-being, worldwide. And these gains can be preserved and enlarged, because the world population is stabilizing.
On the negative side, self-consistency makes the Universe a rough place. It turns out that gravity is probably a consequence of the laws of thermodynamics and the existence of quantum fields like photons, leptons and baryons. In other words, if you want to have light to see by, a planet to stand on, and air to breathe, then self-consistency demands that the Universe be subject to the law of increasing entropy. Which means that things must run down. Which means that you (along with everything in the Universe, including the Universe itself) have to die someday.
To a religious person, it might seem as if we have been dumped into this Universe, where bad things happen, and where we do bad things to each other. God has dropped us from his embrace, kicked us out of Eden. This feels like a punishment, and theologians have rationalized that it happens because we deserve it. Or rather, our earliest ancestors did something to deserve it, which changed them in some way that we have inherited, which makes us deserve it also.
Any abandoned child will try to figure out what it did to cause its abandonment, so as to make amends and get its parent back. It is too threatening to think of the parent as bad, because the parent is the only one who can guarantee child's survival. So the child thinks that it must be bad, and that it must do something good to attract the parent to care for the child again. That, without commenting on its truth, is the level of explanation of the Christian doctrine of Original Sin, and why the doctrine has such mythic, psychological power.
The truth of the doctrine of Original Sin is as a primitive, or rather primal, descriptive psychology. We act like the Doctrine says we act. We often treat ourselves, each other, and the world around us and its inhabitants badly, and we live most aspects of our lives as if God does not exist. Even those of us who are regularly attend church, synagogue, or mosque.
If we are being punished for it, the punishment was around long before we were. The overwhelming weight of the evidence is that evolution is the response of populations of living things to suffering and death. We humans are one instance of that ongoing response. For a religious person, that means that God used suffering and death to create humans. The Human Condition is not so much a punishment as an opportunity.
And, as I argued in the third paragraph of this section, we have taken advantage of that opportunity, at least in a material sense. We are beginning to do very well indeed. We have gone from a population of perhaps a few tens to 7 billion in just 200,000 years by learning to use the self-consistency of the Universe to change our world in our favor. This has been devastating to the world's mega-fauna, including the other human species (e.g. the Neanderthals - perhaps playing the original role of Abel, with our ancestors as Cain) with which we once shared this planet, but I'll just chalk that up to Original Sin for now.
On to Part 3.