Of old, St. John wrote that "if any man love the world, the love of the Father is not in him." In its outward aspect, the world has greatly changed since these words were written. And yet they are as true in the twentieth century as they were in the first. The world has adopted Christian language and manners and modes of thought. But always and everywhere it is to be detected by its antagonism to the Christian estimate of sin. The spirit which accuses Christianity of gross exaggeration in this respect, is the very spirit of the world. Now, as in days of long ago, when torture and death hung on the refusal to scatter a few grains of incense before the statue of Caesar, the same eternal choice is presented to a man, Christ or the world? Which estimate of sin are you going to make your own, the world's, as a lamentable mistake, or failure, or necessity; or the Christian, "worse than any conceivable pain"? It is not a matter of academic interest, but an intensely vital and practical one, affecting a man's whole outlook upon life. Which is right--there is the clear and definite issue raised--the Christian estimate, or the world's estimate of sin? Is it worse than a blunder, a misfortune, a fault? Is it something interwoven into the very structure of our present stage of existence? Or, is it an alien and flagrant intruder into a world where it has no business, which is so constructed that, sooner or later, wilful transgression meets with the direst penalties? There is no question as to what is the Christian estimate of sin. Christ or Caesar? is the issue still presented. But, we wish to ask, is there any reason for believing that the Christian estimate is true? I bring forward three reasons, based respectively on experience, on conscience, on the ultimately similar views of the origin and nature of sin given by science and in the Bible.