Perestroika takes the theme of abandonment and goes to town with it. We watch as those who were abandoned in Millennium Approaches turn the tables on their abandoners, rejecting the deserters' attempts to come back. The abandoned grow strong over the course of the play, finding strength in their isolation. Perestroika also takes the theme of abandonment to the cosmic level: we learn that the entire human race, plus the angels in Heaven, have all been abandoned by God. One of the things that makes Angels in America so brilliant is the way the play manages to simultaneously explore the same themes on an interpersonal, political, and cosmic level.
Prior longs for some kind of universal justice system that punishes those who abandon others, but no such system exists.