It is necessary, therefore, to prove clearly that in the Early Church, at least, Christianity was no whit behind other great religions in possessing a hidden side, and that it guarded, as a priceless treasure, the secrets revealed only to a select few in its Mysteries. But ere doing this it will be well to consider the whole question of this hidden side of religions, and to see why such a side must exist if a religion is to be strong and stable; for thus its existence in Christianity will appear as a foregone conclusion, and the references to it in the writings of the Christian Fathers will appear simple and natural instead of surprising and unintelligible. As a historical fact, the existence of this esotericism is demonstrable; but it may also be shown that intellectually it is a necessity.
The first question we have to answer is: What is the object of religions? They are given to the world by men wiser than the masses of the people on whom they are bestowed, and are intended to quicken human evolution. In order to do this effectively they must reach individuals and influence them. Now all men are not at the same level of evolution, but evolution might be figured as a rising gradient, with men stationed on it at every point. The most highly evolved are far above the least evolved, both in intelligence and character; the capacity alike to understand and to act varies at every stage. It is, therefore, useless to give to all the same religious teaching; that which would help the intellectual man would be entirely unintelligible to the stupid, while that which would throw the saint into ecstasy would leave the criminal untouched. If, on the other hand, the teaching be suitable to help the unintelligent, it is intolerably crude and jejune to the philosopher, while that which redeems the criminal is utterly useless to the saint. Yet all the types need religion, so that each may reach upward to a life higher than that which he is leading, and no type or grade should be sacrificed to any other. Religion must be as graduated as evolution, else it fails in its object.
Next comes the question: In what way do religions seek to quicken human evolution? Religions seek to evolve the moral and intellectual natures, and to aid the spiritual nature to unfold itself. Regarding man as a complex being, they seek to meet him at every point of his constitution, and therefore to bring messages suitable for each, teachings adequate to the most diverse human needs. Teachings must therefore be adapted to each mind and heart to which they are addressed. If a religion does not reach and master the intelligence, if it does not purify and inspire the emotions, it has failed in its object, so far as the person addressed is concerned.