He now returned to Rome, where he appears to have acquired the reputation of a changed character. In due time he procured an appointment to one of the lower ecclesiastical offices; and as he possessed much talent, he did not find it difficult to obtain promotion. When Zephyrinus was advanced to the episcopate, Callistus, who was his special favourite, became one of the leading ministers of the Roman Church; and exercised an almost unbounded sway over the mind of the superficial and time-serving bishop. The Christians of the chief city were now split up into parties, some advocating the orthodox doctrine of the Trinity, and others abetting a different theory. Callistus appears to have dexterously availed himself of their divisions; and, by inducing each faction to believe that he espoused its cause, managed, on the death of Zephyrinus, to secure his election to the vacant dignity. When Callistus had attained the object of his ambition, he tried to restore peace to the Church by endeavouring to persuade the advocates of the antagonistic principles to make mutual concessions. Laying aside the reserve which he had hitherto maintained, he now took up an intermediate position, in the hope that both parties would accept his own theory of the Godhead. "He invented," says Hippolytus, "such a heresy as follows. He said that the Word is the Son and is also the Father, being called by different names, but being one indivisible spirit; and that the Father is not one and the Son another (person), but that they both are one and the same.... The Father, having taken human flesh, deified it by uniting it to Himself,... and so he said that the Father had suffered with the Son." [348:1]