The first half -- God creating the universe, the Sun, Moon, and planets (click the first thumbnail) -- was unveiled in 1510 to vast acclaim, not so much for the figures' massive structural nudity but rather for their intensity and energy. Contrasted with the static hagiography and iconography of previous sacred art, Michelangelo's God is a dervish of creativity, robes a-swirl, pointing a demanding figure at the Sun and saying, "Let there be light!"
Though the Last Judgment, painted 1535-41, is similarly energetic, its mood is darker. (, click on the first image for the full picture.) The risen Christ, a rippling mesomorph, rushes naked into the foreground, dismissing the damned with a violent forearm gesture -- if you have not been with me, to Hell with you! (click the fourth thumbnail.)
While the saved rise from their graves as newly born, the damned are dragged into the abyss. A solitary figure, perhaps the most famous face in the entire composition (and, I think, the only one facing the viewer) looks into the abyss, left hand covering his despairing eyes and mouth. (click the eighth thumbnail.)
The Reformation had started in 1524, just six years earlier, and I speculate that much of Pope Julius' satisfaction with this Last Judgment is its powerful Counter-Reformational message and validation that there is no time for debate, no prospect of backsliding, you are either for us or you are against us, there is no in between.