Actually, by now this Onion piece seems eerily prescient of what actually is going on in Japan!
About the Onion brand of humor: It is harsh. There is always irony and bitter truth in almost every story. In this case, there are plenty of people in this country who truly believe that sanctioned gay marriage provokes the Wrath of the Lord. The Onion hangs them out to dry by making their fondest dream literally come true, with sober and reporterly detail. This is what is known as satire.
Jonathan Swift's "A Modest Proposal for Preventing the Children of Poor People in Ireland From Being a Burden to Their Parents or Country, and for Making Them Beneficial to the Public," published in 1729, is precisely the same sort of piece, and even nastier. And the style goes back to Rome and Greece, if not the stone age.
The Onion's choice of Davenport as the focal point of heavenly retribution was funny because of Davenport's reputation as a provincial, conservative midwestern town, a sister city to Peoria, Waukegan or Podunk. The same joke, set in L. A. or New York or San Francisco, wouldn't scan at all.