Lastly, the Christian faith, itself, was more enduringly attractive than rival worships. Its ritual was simple, as yet, and made no such appeal to eyes and ears as the official pagan cults. It was no respecter of persons, but neither were the worships of Isis and Mithra and kindred cults, which ignored the distinction between rich and poor, between free and bond. If Christianity held out a no less confident promise of an individual future life, its entrance fee to heaven was higher. But, herein, perhaps lay the very secret of its success. Though it is exceedingly difficult to appraise the relative moral standards of Christians, Jews, and pagans in the Roman Empire, significant testimony in favor of the Christians was given by one of their most determined opponents, the emperor Julian (361-363), when he exhorted the pagans to imitate their practical helpfulness in such matters as tending the sick and relieving the poor. Though the pagan world had once possessed an excellent tradition respecting the obligations of wealth, it munificence had tended to be too ostentatious and indiscriminate and, with the general impoverishment of the Roman world in the third and fourth centuries, it shrank to very slender proportions. If the Christian social conscience was more effectively awake at this period than that of the pagans, the success of the church in making and keeping converts has a ready explanation.
From: A History of Rome Down to the Reign of Constantine by M. Cary; 2nd edition (London: Macmillan & Co., Ltd., 1954), pp. 764-765. The first edition was published in 1935.