This is from some old posts over on Quoteland:
From the Alt.Usage.English FAQ: "Desiderata" was written in 1927 by Max Ehrmann (1872-1945). In 1956, the rector of St. Paul's Church in Baltimore, Maryland, used the poem in a collection of mimeographed inspirational material for his congregation. Someone who subsequently printed it asserted that it was found in Old St. Paul's Church, dated 1692. The year 1692 was the founding date of the church and has nothing to do with the poem. See Fred D. Cavinder, "Desiderata", TWA Ambassador, Aug. 1973, pp. 14-15.
Sometime between September 1, 1952 and 1956, A Rev. Frederick Kates, dean of St. John's Cathedral of Spokane, Washington came across a copy of Desiderata without a copyright notice. On June 1, 1956 Rev. Kates became the rector of St. Paul's Church, Baltimore. This church had been founded in 1692. During the Lenten season of 1959 or 1960 Rev. Kates included the poem on a sheet of devotional material he passed out to about 200 members of his congregation. At the top of the page of this handout containing the poem was the notation: "Old St. Paul's Church, Baltimore A.C. 1692." This explains the source of the erroneous attribution which appeared on many following publications of the prose poem Desiderata.