Roberts was also involved in debates within the Christadelphian movement, which in some cases resulted in divisions. For example, 1865 marked separation from George Dowie of Edinburgh who was teaching the doctrine of the existence of a supernatural devil. Roberts' brother-in-law, William Norrie, initially sided with Dowie, but Dowie's group did not long survive his death. As an "Arranging Brother" of Birmingham Temperance Hall Ecclesia he was directly involved in the compilation of the Birmingham Statement of Faith (1877), and by letter from overseas agreed with minor amendation to the "BASF" () in 1898.