To attempt in these days a definition of religion may seem like taking a wanton risk of intellectual confusion. Even a rough classification of religions is difficult. The mass of data is so vast, the varieties of religion so manifold, that no sooner has a scheme of classification established itself than it begins to sag under the weight of material thrown upon it. The old schemes which hinged on a fixed distinction between the religion of the Bible and all religions outside the pale of Biblical revelation, succeeded by dint of excluding a large part of the phenomena. But, as things are with us, no classification is better than a working hypothesis into which, as a constituent element, enters the knowledge of its own mortality.