This is an extract from Christianity and Liberalism by J. Gresham Machen that describes the power of the Gospel. Enjoy!
Chapter 2: Doctrine Page 48:
From the beginning, Christianity was certainly a way of life; the salvation that it offered was a salvation from sin, and salvation from sin appeared not merely in a blessed hope but also in an immediate moral change. The early Christians, to the astonishment of their neighbors, lived a strange new kind of life–a life of honesty, of purity and of unselfishness. And from the Christian community all other types of life were excluded in the strictest way. From the beginning Christianity was certainly a life.
But how was the life produced? It might conceivably have been produced by exhortation. That method had often been tried in the ancient world; in the Hellenistic age there were many wandering preachers who told men how they ought to live. But such exhortation proved to be powerless. Although the ideals of the Cynic and Stoic preachers were high, these preachers never succeeded at transforming society. The strange thing about Christianity was that it adopted an entirely different method. It transformed the lives of men not by appealing to the human will, but by telling a story; not by exhortation, but by the narration of an event. It is no wonder that such a method seemed strange. Could anything be more impractical than the attempt to influence conduct by rehearsing events concerning the death of a religious teacher? That is what Paul called “the foolishness of the message.” It seemed foolish to the ancient world, and it seems foolish to liberal preachers today. But the strange thing is that it works. The effects of it appear even in this world. Where the most eloquent exhortation fails, the simple story of an event succeeds; the lives of men are transformed by a piece of news.
It is especially by such transformation of life, today as always, that the Christian message is commended to the attention of men. Certainly, then, it does make an enormous difference whether our lives be right. If our doctrine be true, and our lives be wrong, how terrible is our sin! For then we have brought despite upon the truth itself. On the other hand, however, it is also very sad when men use the social graces which God has given them, and the moral momentum of a godly ancestry, to commend a message which is false. Nothing in the world can take the place of truth.