The 1969 reform of the General Roman Calendar changed Sept. 29 to the feast of the Archangels — St. Michael, St. Gabriel and St. Raphael — each of whom previously had his own feast day.

Yet a pleasant surprise came on Sept. 29, the feast day of St. Michael the Archangel, when Mr. Trump shared, without comment, a well-known prayer to the great saint.

The Feast of St Michael and All Angels (Michaelmas) falls on 29 September and the texts of the day are uniquely dramatic and visionary. Describing the angelic host and the war in heaven, they have ...