In 1849, the American Protestant Society, the Foreign Evangelical Society, and the Christian Alliance merged to form the American and Foreign Christian Union (AFCU). The object of the AFCU, as stated in its constitution, was "by Missions, Colportage, the Press, and other appropriate agencies, to diffuse and promote the principles of Religious Liberty, and a pure and Evangelical Christianity, both at home and abroad, wherever a corrupted Christianity exists." A chief target of these intentions was the Roman Catholic population of Europe and Latin America.  

The Home Department of the AFCU oversaw the work within the United States among Mexican-Americans in Texas and immigrant populations in New York state and a number of cities, including Chicago, Cincinnati, Louisville, New Orleans, St. Louis, and Philadelphia. The Foreign Department maintained missionaries in France, Italy, Hungary, Greece, Spain, Mexico, and Chile. By 1884, with financial support decreasing for its home and foreign missionary efforts, the organization reorganized and focused its efforts primarily on support of the American Church in Paris and, beginning in 1914, the American Church in Berlin.

The American Churches in Paris and Berlin were set up as non-denominational centers of ministry to the American communities in those cities. The American Church in Berlin has its origins in the mid-nineteenth century, when American residents of the city began to meet for English language worship. In 1902, a church building was dedicated in Berlin-Schoeneberg, near Nollendorfplatz.  Efforts to affiliate the church with the American and Foreign Christian Union began in 1889, and in 1914, the AFCU began its role as steward of the Berlin Church Fund, a trust to support the church. The church closed in 1916, and when it reopened in 1921, the AFCU agreed to take ownership of the American Church building. The church closed again in 1941, and the building was destroyed in the Allied bombing of Berlin in 1944. The lot was sold in 1956, with the proceeds of the sale going to the trust. After the war, the congregation shared facilities with several German churches, until 1964, when it settled in the Old Village Church (Alte Dorfkirche) of the Paulus Community. In 1969, upon the death of its pastor, Arthur Siebens, the church became defunct. Many of the remaining congregants joined the Lutheran American Church in Berlin, and this relationship was formalized in the mid-1970s, with funds from the Berlin Church Fund, still administered by the AFCU, used to support that congregation.  In 1978, the Lutheran American Church in Berlin changed its name to the American Church in Berlin. In 2002, the congregation moved into the Luther Church, very near the Nollendorfplatz property of the old church. Researchers interested in a more detailed history may wish to consult Stewart W. Herman's American Church in Berlin: A History (2001).

The American Church in Paris traces its roots back to 1814, when Americans in Paris began worshipping together. In 1857, under a charter from the government of Napoleon III, the AFCU formally organized the American Chapel, and built a sanctuary on the Rue de Berri, near the Champs-Elysées.  By 1923, the congregation had outgrown the aging building, and, under the leadership of the Rev. Joseph W. Cochran, the congregation began construction of a new building on the Quai d'Orsay, on the Left Bank of the Seine. The new church was dedicated in 1931. The church remained open throughout World War II, though attendence dwindled dramatically, the building's roof was damaged by shell fragments, and the German Red Cross and the German Army requisitioned the building's basement and gymnasium. When the United States entered the war, French pastors held services in the church, and after the war it served U.S. military forces posted in Berlin. The church provided classrooms and office space to the newly established American College in Paris from 1961 until the early 1970s. The American Church in Paris is the oldest American church established outside of the United States. For further historical information, researchers may consult Ruth Dixon's A Church on the Seine: The American Church in Paris, 1814-1981 (1981).