Lerond Curry has traced the major trends in this fifty-year period and analyzed the underlying factors that influenced them. Much of his account is based on correspondence and personal interviews with people who took part in the events and movements he describes.
The rapid growth of Catholic population just before World War I, along with increasing urbanization and tensions related to the war itself, produced a period of intense religious conflict often expressed in violence. After the campaign of 1928, religious leaders made earnest efforts to ameliorate these conflicts, but with the appointment of a United States representative to the Vatican in 1939, hostilities again arose. Nevertheless, Curry finds that in the middle fifties more mature interfaith relationships began to appear, and after Vatican Council II, Protestant-Catholic dialogue developed a new depth.