profoundly concerning Christianity one needs to have had the Christian experience.  But this is very different from saying that to speak worthily of the Christian religion, one must needs have made his own the statements of religion which men of a former generation may have found serviceable.  The distinction between religion itself, on the one hand, and the expression of religion in doctrines and rites, or the application of religion through institutions, on the other hand, is in itself one of the great achievements of the nineteenth century.  It is one which separates us from Christian men in previous centuries as markedly as it does any other.  It is a simple implication of the Kantian theory of knowledge.  The evidence for its validity has come through the application of historical criticism to all the creeds.  Mystics of all ages have seen the truth from far.  The fact that we may assume the prevalence of this distinction among Christian men, and lay it at the base of the discussion we propose, is assuredly one of the gains which the nineteenth century has to record.

It follows that not all of the thinkers with whom we have to deal will have been, in their own time, of the number of avowedly Christian men.  Some who have greatly furthered movements which in the end proved fruitful for Christian thought, have been men who in their own time alienated from professed and official religion.  In the retrospect we must often feel that their opposition to that which they took to be religion was justifiable.  Yet their identification of that with religion itself, and their frank declaration of what they called their own irreligion, was often a mistake.  It was a mistake to which both they and their opponents in due proportion contributed.  A still larger class of those with whom we have to do have indeed asserted for themselves a personal adherence to Christianity.  But their identification with Christianity, or with a particular Christian Church, has been often bitterly denied by those who bore official responsibility in the Church.  The heresy of one generation is the orthodoxy of the next.  There is something perverse in Gottfried Arnold’s maxim, that the true Church, in any age, is to be found with those who have just been excommunicated from the actual Church.  However, the maxim points in the direction of a truth.  By far the larger part of those with whom we have to do have had acknowledged relation to the Christian tradition and institution.  They were Christians and, at the same time, true children of the intellectual life of their own age.  They esteemed it not merely their privilege, but also their duty, to endeavour to ponder anew the religious and Christian problem, and to state that which they thought in a manner congruous with the thoughts which the men of the age would naturally have concerning other themes.