The Christadelphian founder lived in a time in America where there was a strong expectation by many on the imminent return (or Second Advent) of Christ. This is not a new belief and there are many references in the New Testament which show early Christians believed Christ would return soon too. Many groups through history have focused on the advent as the prime focus of scripture (particularly in times of abrupt change) and the 1800s was a period of intense speculation about the date of Christ’s actual return to the earth. Using time periods referred to in the books of Daniel and Revelation and using principles of “a day for a year” and various starting points, various dates were suggested for when he would return. One in particular was an event now called The Great Disappointment when thousands believed Jesus would return in 1844.
Many new denominations, including the Adventist movement, the Jehovah’s Witnesses, the Worldwide Church of God and the Christadelphians have links to this period and the various movements which emerged from it when the expected return never occurred. In the case of the Adventists and the Jehovah’s Witnesses belief in a spiritual (or invisible return of Christ have emerged) that has been fitted into date scenarios to explain why Christ never returned at certain times expected.
In “The Rise of the Cults”, Branson Hopkins, a former Christadelphian has researched some of these links in detail and has documented the fact that many of the leaders of the various emerging denominations had links, corresponded with each other and were sometimes in the same churches. I suggest a huge amount more work will subsequently be necessary to fully understand major links. Many of these will be found because all of these movements have significant archives of material relating to their origins.