An infidel was speaking to a Christian. His angry, sarcastic words were: "The gospel you preach has not done much good in the world. There is plenty of wickedness and suffering wherever one goes. I don't believe in your religion and won't have it."
The two walked on a little further. Presently they passed a very dirty little boy playing in the mud. Said the Christian to the infidel (who happened to be a soap manufacturer): "Your soap has not done much good in the world. See, that boy is filthy, and there is plenty of dirt in the world. I don't believe in your soap."
"But," said the soap manufacturer, "my soap is all right, if it is applied."
"Just so," replied the Christian, “‘the gospel of Christ... is the power of God unto salvation to every one that believeth.' All who have believed have found out the truth of these words. The trouble with you is, you have never applied the gospel to your own soul, any more than that dirty boy has applied your soap to his body."