The key of the difficulty is on its other side, in the doctrine of the unity of God, which was not only taught by Jews and Christians, but generally admitted by serious heathens. The philosophers spoke of a dim Supreme far off from men, and even the polytheists were not unwilling to subordinate their motley crew of gods to some mysterious divinity beyond them all. So far there was a general agreement. But underneath this seeming harmony there was a deep divergence. Resting on a firm basis of historic revelation, Christianity could bear record of a God who loved the world and of a Redeemer who had come in human flesh. As this coming is enough to show that God is something more than abstract perfection and infinity, there is nothing incredible in a real incarnation, or in a real trinity inside the unity of God. But the heathen had no historic revelation of a living hope to sustain him in that age of failure and exhaustion. Nature was just as mighty, just as ruthless then as now, and the gospel was not yet the spring of hope it is in modern life. In our time the very enemies of the cross are living in its light, and drawing at their pleasure from the well of Christian hope. It was not yet so in that age. Brave men like Marcus Aurelius could only do their duty with hopeless courage, and worship as they might a God who seemed to refuse all answer to the great and bitter cry of mankind. If he cares for men, why does he let them perish? The less he has to do with us, the better we can understand our evil plight. Thus their Supreme was far beyond the weakness of human sympathy. They made him less a person than a thing or an idea, enveloped in clouds of mysticism and abolished from the world by his very exaltation over it. He must not touch it lest it perish. The Redeemer whom the Christians worship may be a hero or a prophet, an angel or a demi-god--anything except a Son of God in human form. We shall have to find some explanation for the scandal of the incarnation. [Sidenote: Arius himself.]