The penultimate Trump

"The Last Trump" is a science fiction short story by American writer Isaac Asimov. It was first published in the June 1955 issue of Fantastic Universe and reprinted in the 1957 collection Earth Is Room Enough. Although humorous, it deals inter alia with a serious subject, calendar reform.

Plot summary
By order of the Council of Ascendants and approved of by the Chief, it is decided that the Day of Resurrection is due on Earth, despite the protestations of Etheriel, a junior Seraph with responsibility for the world. Whilst he seeks an audience with the Chief to plead for a stay of execution for "his" planet, the Last Trump is sounded, and as of January 1, 1957, time comes to a stop on Earth.

A mysterious figure known only as R. E. Mann (a pun on Ahriman, the Persian name for Satan) makes his way across the world, seeing what has happened in the Hereafter and pleased with it. All the dead are coming back to life, naked and uncaring. He meets a former professor of history who observes that the people have indeed been judged and are not in heaven but hell.

Etheriel has his meeting with the Chief and argues that the date January 1, 1957, unqualified, is meaningless and that therefore the Day of Resurrection is meaningless. The Chief agrees and declares that it will come only when all the peoples of the Earth agree on a common date (which, given the wide variety of cultures on Earth, is extremely unlikely to ever occur). The world is instantly restored to normality.

R. E. Mann, frustrated in his endeavours, plans to promote the adoption of a new calendar system, based on the Atomic Era, to begin on December 2, 1944.

So now you know.