In adopting Christianity, Europe exchanged a religion in which one god, or one story about a god, was about as good as another, for a religion which claimed a definite, historical founder who had left behind him a corporate teaching body, the Church. To such a body, the out-and-out pagan or disbeliever is an open and possibly generous enemy. Whereas he who proclaims himself a fellow Christian, but meanwhile falsifies the Church’s doctrine by twisting and altering it to suit himself, is a traitor, a snake in the grass compared to whom the heathen is an angel of light. Leaving on one side all discussion as to the damnation of the heathen, the fact remains that the Christian Church is bound to maintain her faith and practice as an essential, nay the essential, of human life. Otherwise she has no reason for being at all. She must, therefore, contend especially against the heretic, the enemy from within, who would disfigure the faith by which she lives; and she has done so, from the “false teachers” and “heretics” whom St. Paul so often urged his flock to avoid, down to the poor creatures who would reduce her Saviour to the stature of a “social uplifter” or the walking delegate of a labor union. To keep the faith is a perpetual warfare. Make what you will of the body empowered to interpret and define Christian doctrine and of the means of defending that doctrine when defined: the necessities of some sort of definition and authority will remain as long as the Christian name endures.