There are two sides to Adventism, one liberal and other conservative. One side of Adventism comes from the Miller movement, with its interest in time prophecies, setting dates, condemning the churches as Babylon, and separating from all who disagreed with them on the definite time; writing books and publishing papers on the time proofs, with charts, finding prophetic fulfillment in contemporary events. Barbour followed in the footsteps of Miller and the original Miller movement, and Russell took this over from Barbour.
However, there is another side to Adventism which was more liberal and broadminded, perhaps exemplified by George Storrs. Storrs had been a prominent Methodist minister, was one of the prominent Millerite preachers, and was mainly responsible for introducing conditionalism among the Adventists. Storrs' motto was "Prove all things", was against organization and sectarianism. Other Adventists were Arian in their views, congregational in church government, opposed to church names such as Adventist. H. L. Hastings published a journal "The Christian", and was interested in defending against infidelity, and was interdenominational in his activities. Russell writes that he became infidel as a youth, and I have suspected that Russell had read Hastings, and drew on his writings for source material, but I have not found enough of Hastings' writings to confirm this.
Storrs, besides teaching against eternal torment, also advocated a future probation for all the unsaved, emphasizing the love of God. Storrs had contacts with many outside of Adventism, and was familiar with the writings of British authors, and acted as a point of contact and conduit for alternative opinions. Storrs denied the personality of the devil, was noncommital on the Trinity. I think that Storrs was also Anglo-Israelite, but I am not sure on this point. There were Adventists that did not believe in the substitutionary atonement, and Barbour and Paton picked up this idea that floating among the Adventists at the time. C. T. Russell opposed this.
Russell combined both sides of Adventism, the conservative/Barbourite/Millerite side, and the liberal/Storrs/independent/broadminded side. But it was an uneasy mixture, and caused conflicting attitudes, and doublespeak.