The circumstances which at this time were tending to make Judaism a proselytizing religion were also preparing it for success in its mission. The religion of the prophets was too pure to become popular. The absence of supernaturalism, the freedom from dogma, which made it in essence so superior to Christianity, rendered it fit only for the highest minds. Afterwards, when impressed on Israel in general, it was identified with a rigid ceremonialism. That such a religion, deriving no strength from formalism or from national feeling, could conquer the Gentile world, far lower than the Jewish people in religious development, was of course impossible. But just at this moment it began to receive additions from foreign sources which ultimately bridged the chasm between it and the ideas of ordinary men. The dispersion of the Jews, which completed the victory of Judaism, alloyed it with baser elements. So far as its adherents were placed in contact with idolatrous religions like the Chaldean, it was rather secured against corruption. In the Persian religion, however, which it encountered towards the close of the captivity, it found an enemy disguised as a friend. This religion, which was as anti-idolatrous as the Jewish, and which had a nominal monotheism underlying its dualism, was marked by a supernaturalism very different from the simplicity of the religion of the prophets. A large part of this supernaturalism was now transferred to Judaism. The Persian deity of evil became the Jewish Satan, with a multitude of demons under him that made man their sport and prey.[48] A hierarchy of angels was constructed, completely foreign to the prophetic belief in the immediate agency of God. But the most important doctrine at this time introduced into Judaism, whether from the Persian religion or not is a matter of dispute, was the doctrine of the resurrection of the dead, which soon became the chief dogma of the Jewish creed. How far it tended to suit Judaism to Gentile requirements is shown by a curious passage of the Apocrypha, which reads like a description of the doctrine of Pagan Christianity respecting purgatory and masses for the dead.[49] The more philosophical Jews afterwards formed themselves into a party to resist these innovations, but the majority of the people eagerly adopted them. With the spiritual Messianic ideal they were readily connected, as they formed the popular elements needed for proselytism, and as they tended to place religion on a personal rather than on a national basis. We find them the chief strength of Christianity, which, as the successful embodiment of the outward forces of Judaism, naturally laid aside the portions of it unfavourable, and took up the portions of it favourable, to denationalisation and expansion.