A moment's thought will show how the teaching that Yahweh alone was to be worshipped broke away from the main stream of Semitic belief, and prepared the way for the ultimate prevalence of the belief that God was one. That He was supersensuous, so that He could not rightly or adequately be represented by any likeness of anything in heaven or earth or sea, left no possible outlet for thought about Him, save in the direction that He was a Spirit. In essence consequently the spirituality of God was thereby secured. Still more important perhaps was the conception of Yahweh as the Helper and Deliverer, the Saviour of His people; for this at once suggested the thought that the true bond between God and man was not mere necessity, nor mere dependence upon resistless power, but love--love to a Divine Helper who revealed Himself in gracious acts and providences, and who longed after and cared for His people with a perfectly undeserved affection. Lastly, His holiness and faithfulness, His righteousness in fact, held implicit in it His supremacy and universality. As Wellhausen has said, "As God of justice and right, Yahweh came to be thought of as the highest, and at last as the only power in heaven and earth." Whether that last stage was present to the mind of Moses, or of any who received the commandments in the first place, is of merely secondary importance. At the very least, the way which must necessarily lead to that stage was opened here, and the mind of man entered upon the path to a pure monotheism, a monotheism which separated God from the world, and referred to His will all that happened in the world of created things. God is One, God is a Spirit, God is Love, and God rules over all--these are the attributes of Yahweh as the Decalogue sets them forth; and in principle the whole higher life of humanity was secured by the great synthesis.
Like all beginnings, this was an achievement of the highest kind. Nowhere but in the soul of one Divinely enlightened man could such a revelation have made itself known; and the solitude of a lonely shepherd's life, following upon the stir and training of a high place in the cultured society of Egypt, gave precisely the kind of environment which would prepare the soul to hear the voice by which God spoke. For we are not to suppose that this revelation came to Moses without any effort or preparation on his part. God does not reveal His highest to the slothful or the debased. Even when He speaks from Sinai in thunder and in flame, it is only the man who has been exercising himself in these great matters who can understand and remember. All the people had been terrified by the Divine Presence, but they forgot the law immediately and fell back into idolatry. It was Moses who retained it and brought it back to them again. His personality was the organ of the Divine will; and in this law which he promulgated Moses laid the foundation of all that now forms the most cherished heritage of men. The central thing in religion is the character of God. Contrary to the prevailing feeling, which makes many say that they know nothing of God, but are sure of their duty to man, history teaches that, in the end, man's thought of God is the decisive thing. Everything else shapes itself according to that; and by taking the first great steps, which broke through the limits of mere naturalism, Moses laid the foundation of all that was to come. There was here the promise and the potency of all higher life: love and holiness had their way prepared, so that they should one day become supreme in man's conception of the highest life: the confused halting between the material and the spiritual, which can be traced in the very highest conceptions of merely natural religions, was in principle done away. And what was here gained was never lost again. Even though the multitude never really grasped all that Moses had proclaimed Yahweh to be; and though it should be proved, which is as yet by no means the case, that even David thought of Him as limited in power and claims by the extent of the land which Israel inhabited; and though, as a matter of fact, the full-orbed universality which the ten commandments implicitly held in them was not attained under the old covenant at all; yet these ten words remained always an incitement to higher thoughts. No advance made in religion or morals by the chosen people ever superseded them. Even when Christ came, He came not to destroy but to fulfil. The highest reach of even His thoughts as regards God could be brought easily and naturally under the terms of this fundamental revelation to Israel.