When we read the apologetics of the second and third centuries, can we altogether avoid the painful impression that what we have here—as though the persecuted can only regard themselves as spiritually undeserving of the external pressure brought to bear on them—is, on the whole, a not very happy, a rather self-righteous, and at any rate a not very perspicacious boasting about all those advantages of Christianity over heathen religion which were in themselves incontestable but not ultimately decisive? In these early self-commendations of Christianity a remarkably small part is played by the fact that grace is the truth of Christianity, that the Christian is justified when he is without God, like Abraham, that he is like the publican in the temple, the prodigal son, wretched Lazarus, the guilty thief crucified with Jesus Christ. Instead, we have the—admittedly successful—rivalry of one way of salvation, one wisdom and morality with others, of a higher humanity consummated and transfigured by the cross of Christ with a decadent and defeated humanity which has rightly grown weary of its ancient ideals. How strangely did a man like Tertullian see the danger which threatened at this point, and at the same time never really see it at all, but actually help to increase it. And to the extent that the fact that grace, that Jesus Christ, is the truth of Christianity was never completely concealed in the doctrine and proclamation of the Church, did not the fact that Christianity is the special religion of grace and redemption easily appear to be its final and supreme advantage, although it was robbed of its real meaning and power to convince by the fact that the Church was not content with grace?
-Karl Barth, Church Dogmatics I.2.17
…Paganism is that view of life which finds the highest goal of human existence in the healthy and harmonious and joyous development of existing human faculties. Very different is the Christian ideal. Paganism is optimistic with regard to unaided human nature’ whereas Christianity is the religion of the broken heart…In saying that Christianity is the religion of the broken heart, we do not mean that Christianity ends with the broken heart; we do not mean that the characteristic Christian attitude is a continual beating on the breast or a continual crying of “Woe is me.” Nothing could be further from the fact. On the contrary, Christianity means that sin is faced once for all, and then is cast, by the grace of God, forever into the depths of the sea. The trouble with the paganism of ancient Greece, as with the paganism of modern times, was not in the superstructure, which was glorious, but in the foundation, which was rotten. There was always something to be covered up; the enthusiasm of the architect was maintained only by ignoring the disturbing fact of sin. In Christianity, on the other hand, nothing needs to be covered up. The fact of sin is faced squarely once for all, and is dealt with by the grace of God. But then, after sin has been removed by the grace of God, the Christian can proceed to develop joyously every faculty that God has given him. Such is the higher Christian humanism—a humanism founded not upon human pride but upon divine grace.
-J. Greshem Machen