Nightfall by Isaac Asimov, Robert Silverberg

this evening. —What is it exactly that the Apostles have said now? I forget.”
    “It was Mondior 71,” said Theremon. “The Grand High Mumbo-Jumbo himself. What he said was—let me think—that the time is very near when the gods intend to purge the world of sin, that he can calculate the exact day, even the exact hour, when doom will arrive.”
    Beenay groaned. “So what’s new about that? Isn’t that what they’ve been saying for years?”
    “Yes, but they’re starting to hand out more of the gory details now. It’s the notion of the Apostles, you know, that this won’t be the first time the world has been destroyed. They teach that the gods have deliberately made mankind imperfect, as a test, and that they have given us a single year—one of their divine years, not one of our little ones—in which to shape up. That’s called a Year of Godliness, and it’s exactly two thousand and forty-nine of our years long. Again and again, when the Year of Godliness has ended, the gods have discovered that we’re still wicked and sinful, and so they have destroyed the world by sending down heavenly flames from holy places in the sky that are known as Stars. So say the Apostles, anyway.”
    “Stars?” Beenay said. “Does he mean the suns?”
    “No, Stars. Mondior says that the Stars are specifically different from the six suns. —Haven’t you ever paid any attention to this stuff, Beenay?”
    “No. Why in the world should I?”
    “Well, in any event, when the Year of Godliness ends and nothing on Kalgash has improved, morally speaking, these Stars drop some sort of holy fire on us and burn us up. Mondior says this has happened any number of times. But each time it does, the gods are merciful, or at least a faction amongthem is: every time the world is destroyed, the kinder gods prevail over the sterner ones and humanity is given one more chance. And so the godliest of the survivors are rescued from the holocaust and a new deadline is set: mankind gets another two thousand and forty-nine years to cast off its evil ways. The time is almost up again, says Mondior. It’s just under two thousand and forty-eight years since the last cataclysm. In something like fourteen months the suns will all disappear and these hideous Stars of his will shoot flame down out of a black sky to wipe out the wicked. Next year on Theptar nineteenth, to be specific.”
    “Fourteen months,” Beenay said in a musing way. “The nineteenth of Theptar. He’s very precise about it, isn’t he? I suppose he knows the exact time of day it’ll happen, too.”
    “So he says, yes. That’s why I’d like a statement from somebody connected with the Observatory, preferably you. Mondior’s latest announcement is that the exact time of the catastrophe can be calculated
scientifically
—that it isn’t simply something that’s set forth as dogma in the Book of Revelations, but that it’s subject to the same sort of computation that astronomers employ when—when—”
    Theremon faltered and halted.
    “When we calculate the orbital motions of the suns and the world?” Beenay asked acidly.
    “Well, yes,” Theremon said, looking abashed.
    “Then maybe there’s hope for the world after all, if the Apostles can’t do any better job of it than we do.”
    “I need a statement, Beenay.”
    “Yes. I realize that.” The next round of drinks had arrived. Beenay wrapped his hand around his glass. “Try this,” he said after a moment. “ ‘The main task of science is to separate truth from untruth, in the hope of revealing the way the universe really works. Putting truth to work in the service of untruth is not what we at the university think of as the scientific way. We are capable now of predicting the movements of the suns in the heavens, yes—but even if we use our best computer, we are no closer than we ever were to being able to foretell the will of the gods. Nor will we ever be, I suspect.’—How’s that?”
    “Perfect,”