By the late 1930s, Coughlin's broadcasts and his magazine, Social Justice, had become vehicles for open antisemitism. He blamed Jewish bankers for the Depression and for the 1917 Russian Revolution. In late 1938, Social Justice printed weekly installments of the Protocols of the Elders of Zion, a fabricated text long used to justify persecution of Jews. After the November 1938 Kristallnacht pogrom in Germany, Coughlin told listeners on November 20 that Jewish persecution had only followed earlier Christian persecution, and on December 5 he broadcast material documented as lifted nearly verbatim from a speech by Nazi propaganda minister Joseph Goebbels. The United States Holocaust Memorial Museum's own research holds Coughlin among the most prominent antisemitic voices in American public life of the era.
The mechanism that ended his career was regulatory rather than criminal. On September 23, 1940, Coughlin announced the cancellation of the Golden Hour program. On April 14, 1942, the Postmaster General suspended Social Justice's second class mailing permit on wartime sedition grounds, cutting off its distribution. On May 1, 1942, Archbishop Edward Mooney of Detroit, acting under authority the Catholic Church held over its own clergy, ordered Coughlin to cease all political activity and confine himself to pastoral duties, under threat of defrocking and possible prosecution. Coughlin was never criminally charged. He remained pastor of the Shrine of the Little Flower, all future public remarks reviewed in advance by the archdiocese, until his retirement in 1966, and died in Bloomfield Hills, Michigan, on October 27, 1979.