Booker's "Rebirth" plot outline starts with the young hero or heroine falling under the shadow of an evil power. Mwa ha ha. At the beginning of the novel, Mike almost literally falls to Earth and under the dark powers of the World Federation. Okay, he actually flies there, but all flying ends with a falling, right? On Earth, the government imprisons Mike in Bethesda Hospital. The hospital is cold, sterile, and removed, and Joe Douglas, Secretary General of the World Federation, drives away Mahmoud and Dr. Nelson, the only friends Mike has on Earth before meeting Jill. Mike's lack of knowledge of human customs prevents him from even realizing his ordeal, let alone fighting back. (The Falling Stage is roughly Part One of the novel.)
After Jill spirits Mike away from Bethesda, the dark powers go into recession (or seem to anyway). Mike is brought to Jubal's house, the epitome of freedom and learning. Jubal's awesome lawyering gives Joe Douglas the run around. At the interplanetary conference, Jubal negotiates it so Mike gets to keep his freedom, and the politicos will more or less leave him alone. Mike gets his happy ending. Crisis averted; game over. Then why is there still so much more book to go? (The Recession Stage is roughly Part Two.)
Mike visits a Fosterite tabernacle and tastes human religion for the first time. Then he leaves Jubal's house and travels the world, taking various jobs and reading from libraries everywhere. He has a stint as a carnie magician and working a casino floor. All the while he learns about human society and culture. Wait, isn't this the imprisonment stage? Since when is globetrotting with tons of cash, limitless time, and a beautiful partner considered imprisoning?
Well, remember the World Federation from the last stage? Turns out they were only a by-product of the novel's actual dark power, societal mores. With Mike now out in the world, he has discovered that the bars of human society extend beyond the laws of government. They are ingrained in people's very character, and the only way to defeat the dark power is to change humanity itself. We're dealing with some Alanis Morissette levels of irony here. (You guessed it, roughly Part Three.)
The nightmare stage begins when Ben visits Mike's Nest. At first glance, this might seem counterintuitive. Mike's church is doing well, he is bringing new disciples into the fold, and Ben, who initially rejected Mike's views, joins the group after a heart-to-heart with Jubal. Things appear to be going swell for Mike and company. Where's the nightmare?
When the church is set on fire, the truth begins to be revealed. Much of the world outside Mike's church resents our Martian and his philosophical views. Mike worries he has failed in his task to bring true, meaningful change to the world. So the imprisonment is a double-whammy: one of social constraint and inner fear. With this information, we can look back on Ben's visit to the Nest and see the true nightmare and how well Mike kept it hidden from those close to him. (This stage takes place roughly during Part Four and the first half of Part Five).
In true Booker fashion, the rebirth comes when Mike's imprisonment in an intolerant human society ends, and he is set free by a woman or child. Only by set free, we mean martyred, and by child, we mean an angry mob—you know, a bunch of angry, shotgun-toting, lynch-mongering children. Yeah…
Okay, so the lack of children might deviate from the traditional Booker plot outline; but Mike is set free by the mob. Truly. When he goes to the afterlife, Mike no longer has to struggle with the constraints of human society. Mike and his ideas even gain acceptance, as we see in Digby's character reversal. Finally, it is strongly hinted at in the novel that Mike might be the Archangel Michael. If this is true, then going to the afterlife would be a rebirth for him since he is returning home. (This corresponds to roughly the second half of Part Five.)