Baptist historian Bruce Gourley outlines four main views of Baptist origins: (1) The modern scholarly consensus that the movement traces its origin to the 17th century via the English Separatists, (2) the view that it was an outgrowth of Anabaptist traditions, (3) the perpetuity view which assumes that the Baptist faith and practice has existed since the time of Christ, and (4) the successionist view, or "Baptist successionism", which argues that Baptist churches actually existed in an unbroken chain since the time of Christ. Who outlined the three main views of Baptist origins?