Greek culture, moreover, and Roman government, as it has often been observed, had greatly tended to unify mankind. They diffused a common atmosphere of thought and established one imperial law round the circuit of the Mediterranean shores. But these conquests of secular civilization, the victories of arms and arts, were achieved at the expense of religion. Polytheism is essentially barbarian. It flourishes in division and in ignorance. To bring together its innumerable gods and creeds was to bring them all into contempt. The _one law_, the _one learning_ now prevailing in the world, created a void in the conscience of mankind, only to be filled by the _one faith_. Without a centre of spiritual unity, history shows that no other union will endure. But for Christianity, the Græco-Roman civilization would have perished, trampled out by the feet of Goths and Huns. The Jewish faith failed to meet the world's demand for a universal religion. It could never have saved European society. Nor was it designed for such a purpose. True, its Jehovah was "the God of the whole earth." The teaching of the Old Testament, as Paul easily showed, had a universal import and brought all men within the scope of its promises. But in its actual shape and its positive institutions it was still tribal and exclusive. Mosaism planted round the family of Abraham a fence of ordinances, framed of set purpose to make them a separate people and preserve them from heathen contamination. This system, at first maintained with difficulty, in course of time gained control of the Israelitish nature, and its exclusiveness was aggravated by every device of Pharisaic ingenuity. Without an entire transformation, without in fact ceasing to be Judaism, the Jewish religion was doomed to isolation. Under the Roman Empire, in consequence of the ubiquitous dispersion of the Jews, it spread far and wide. It attracted numerous and influential converts. But these proselytes never were, and never could have been generally amalgamated with the sacred people. They remained in the outer court, worshipping the God of Israel "afar off" (Eph. ii. 11-22; iii. 4-6).