In the last lecture we traced the growth of Christianity through the three stages that are represented in the New Testament, and we saw that when the new religion passed beyond the bounds of Palestine and entered on a campaign for converts among the Gentiles, it came into contact with Greek philosophic thought and perforce began to state its doctrines in terms which should be intelligible to educated men. For in spite of the fact that the majority of its adherents—like those of every other contemporary religion—were naturally of humble birth and station, it is certain that from the first it appealed also to men of position and education, and that such were among its followers. Therefore when it put forth its claims to be the universal religion, it had to meet and satisfy the demands of the intellectual classes. Not only were the various forms of Greek philosophy rivals of Christianity, but the oriental mysteries also proved serious opponents. In our discussion of the most important of these mystery religions in an earlier lecture we tried to show the reasons for the wide appeal which they made during the first two centuries and a half of our era. Christianity therefore had to offer a greater assurance and satisfaction than these religions if it was to make headway against them. Thus Christianity was forced to meet two classes of opponents. But it was inevitable that while the new religion was seeking to influence the environment into which it had come, it should itself be influenced by the world it had entered. No living belief or institution can exist without being affected by the life of which it is a part. Christianity accordingly ran many dangers, received many accretions, and was in some ways transformed during the first few centuries of its history. In this final lecture we shall consider briefly, by means of significant illustrations, first, the way in which Christianity during the second and third centuries accommodated itself to the intellectual world; secondly, the influence which the pagan environment had on Christian thought; and finally, the causes of its triumph.