Albert Benjamin Simpson held one of the most prestigious pulpits in American Presbyterianism before he gave it up. Born in Canada in 1843 and ordained a Presbyterian minister, Simpson built a substantial congregation in New York City, but grew convinced that conventional pastoral ministry left no room for the evangelistic urgency, the ministry to the urban poor and the mission to unreached peoples abroad that he believed the gospel demanded. In 1881 he resigned his pulpit entirely, choosing to work outside any existing denominational structure rather than try to reform one from within.
Six years of independent evangelistic and missionary work followed before Simpson organized his growing following into two parallel societies in 1887: the Christian Alliance, devoted to deepening believers' spiritual life, and the Evangelical Missionary Alliance, devoted to sending and supporting missionaries. He kept the two deliberately separate at first, one for nurture and one for mission, before merging them into a single organization in 1897 under the name that has lasted since, the Christian and Missionary Alliance.
For most of its history the Alliance understood itself as an interdenominational fellowship and missionary sending agency rather than a denomination in the ordinary sense, drawing members and even ordained clergy from other church backgrounds who remained active in the Alliance's societies alongside their own denominational ties. That arrangement gradually gave way to a more conventional denominational structure over the twentieth century, and in 1974 the Alliance formally adopted denominational status, decades after Simpson's own death in 1919.