There may perhaps be other salient points of differentiation between Christianity and the preceding pagan religions; but for the present we may recognize these two--(a) the tendency towards a renunciation of the world, and the consequent cultivation of a purely spiritual love and (b) the insistence on a morality whose inspiration was a private sense of duty to God rather than a public sense of duty to one's neighbor and to society generally. It may be interesting to trace the causes which led to this differentiation. Three centuries before our era the conquests of Alexander had had the effect of spreading the Greek thought and culture over most of the known world. A vast number of small bodies of worshipers of local deities, with their various rituals and religious customs, had thus been broken up, or at least brought into contact with each other and partially modified and hellenized. The orbit of a more general conception of life and religion was already being traced. By the time of the founding of the first Christian Church the immense conquests of Rome had greatly extended and established the process. The Mediterranean had become a great Roman lake. Merchant ships and routes of traffic crossed it in all directions; tourists visited its shores. The known world had become one. The numberless peoples, tribes, nations, societies within the girdle of the Empire, with their various languages, creeds, customs, religions, philosophies, were profoundly influencing each other. (1) A great fusion was taking place; and it was becoming inevitable that the next great religious movement would have a world-wide character. (1) For an enlargement on this theme see Glover's Conflict of Religions in the early Roman Empire; also S. J. Case, Evolution of Early Christianity (University of Chicago, 1914). The Adonis worship, for instance (a resurrection-cult), "was still thriving in Syria and Cyprus when Paul preached there," and the worship of Isis and Serapis had already reached then, Rome and Naples.