Baptist successionism is the theory that there exists an unbroken chain of churches that have held the beliefs (though not always the name) of the current Baptist churches since the time of Christ. This theory, once commonly held among Baptists, is now mostly identified with Landmarkism, though not exclusively. Some Southern Baptists, Primitive Baptists, Regular Baptists and United Baptists hold a similar view.
This theory is built more on a theological and scriptural foundation rather than a historical one. Much of the historical documentation needed to support this theory has been lost or never existed. It also rejects falsifiability because it only requires the existence of at least one single church (could be as small as two or three people - according to Christ's promise to be with His church where even two or three were gathered together during any particular point in history to be true.
Ancient anti-paedobaptist groups, such as Mennonites, Waldenses, Albigenses, Cathari, and Paulicians, are often considered to be within this chain of tradition. However, some of those mentioned groups that have continued existence up today, such as the Mennonites, Waldenses, and Paulicians, deny any link with the modern Baptist churches and the Albigenses and Cathari (in reality the same group) had views which contrast very sharply with Baptist ones.
John T. Christian's History of the Baptists is general Baptist history written from a successionist perspective. Christian also wrote two other books (Did They Dip? and Baptist History Vindicated) which deal with the narrower question of baptism for immersion among the 16th and 17th century Anabaptists. J. M. Carroll's The Trail of Blood is a widely distributed popular pamphlet promoting Baptist successionism.
A pre-Landmark work defending the concept of successionism is A Vindication of the Continued Succession of the Primitive Church of Jesus Christ (Now Scandalously termed Anabaptist) from the Apostles unto this present time published in England in 1652.