Carefully as Syncretism has been examined in recent years, the clue to its development--the transformation of Eastern Churches into Western cults, and then the reverse process of transformation of Western cults into Eastern Churches--has been missed.[316] Yet without this key it is quite impossible to understand the religious history of Early Christianity. The battle that in Rome was between Christ and Mithras as cult-deities took the form, east of Antioch, of a contest between the Persian and the Christian Churches. But the heaviest battle that Christianity had to fight, after it came itself under the influence of the Pseudomorphosis and began to develop spiritually with its face to the West, was not that against the true Classical deities. With these it was never face to face, for the public city-cults had long been inwardly dead and possessed no hold whatever on men’s souls. The formidable enemy was Paganism, or Hellenism, emerging as _a powerful new Church_ and born of the selfsame spirit as Christianity itself. In the end there were in the east of the Roman Empire not one cult-Church, but two, and if one of these comprised exclusively the followers of Christ, the other, too, was made up of communities which, under a thousand different labels, consciously worshipped one and the same divine principle. Much has been written on the Classical toleration. The nature of a religion may perhaps be most clearly seen in the limits of its tolerance, and there were such limits in Classical religions as in others. It was, indeed, one essential character of these religions that they were numerous, and another that they were religions of pure performance; for them, therefore, the question of toleration, as the word is usually understood, did not arise. But respect for the cult-formalities as such was postulated and required, and many a philosopher, even many an unwitting stranger, who infringed this law by word or deed, was made to realize the limits of Classical toleration. The reciprocal persecutions of the Magian Churches are something different from this; there it was the duty of the henotheist to his own faith that forbade him to recognize false tenets. Classical _cults_ would have tolerated the Jesus-cult as one of their own number. But the _cult-Church_ was bound to attack the Jesus-Church. All the great persecutions of Christians (corresponding therein exactly to the later persecutions of Paganism) came, not from the “Roman” State, but from this cult-Church, and they were only political inasmuch as the cult-Church was both nation and fatherland. It will be observed that the mask of Cæsar-worship covered _two_ religious usages. In the Classical cities of the West, Rome above all, the special cult of the _Divus_ arose as a last expression of that Euclidean feeling which required that there should be legal and therefore sacral means of communication between the body-unit man and the body-unit God.