The historically Black Protestant tradition is the one of Pew Research Center's three Protestant classification families that groups denominations by shared history rather than by shared theology or church government. Its member bodies span the Methodist connectional system of the African Methodist Episcopal Church, the congregational autonomy of the National Baptist conventions, and the more centralized structure of the Church of God in Christ, a Pentecostal holiness body rather than a Methodist or Baptist one. What holds them together in the classification is not doctrine. It is that each was founded by and for Black Christians who were excluded from, or segregated within, white controlled denominations, and that a member of any of them is counted in this tradition by Pew's survey regardless of which specific theology that member holds.
This differs from church family, the atlas's own doctrinal grouping of a denomination by theological lineage rather than by shared history; a denomination's classification family and its church family answer different questions and can differ from each other. Five of the seven denominations C. Eric Lincoln and Lawrence H. Mamiya name as the tradition's historic core are full entities in this atlas: the African Methodist Episcopal Church, the African Methodist Episcopal Zion Church, the Christian Methodist Episcopal Church, the National Baptist Convention of America, and the Progressive National Baptist Convention. Two are not yet entities here: the National Baptist Convention, USA, Incorporated, the tradition's single largest body, and the Church of God in Christ, its largest Pentecostal denomination. Both gaps are named rather than left silent.