Belief in Christ's return or "advent" is stated in the Apostles' and Nicene creeds and thus is part of the Christian tradition. For Adventist groups, however, this is the center of Christian faith. Adventism has roots in nineteenth-century evangelicalism, which looked forward to the "millennium" or thousand-year reign of Christ (Revelation 20:1-6). The Seventh Day Adventists began with William Miller's preaching that the world would end in 1844; Ellen G. White reorganized the movement in 1863. Another Adventist group, the Jehovah's Witnesses, was founded by Charles Russell (1852-1916). The Jehovah's Witnesses anticipate the end of the world by proselytizing and predicting end-times events. A related theme is "dispensationalism," which seeks to decode biblical prophecies by relating them to events on a historical time-line, arranged in distinct chapters or "dispensations." This approach to history is taken by some fundamentalists. Adventist groups have large numbers of adherents worldwide.