1 Thus then does the Lord plainly show that it was the true Lord and the one God who had been set forth by the law; for Him whom the law proclaimed as God, the same did Christ point out as the Father, whom also it behooves the disciples of Christ alone to serve. By means of the statements of the law, He put our adversary to utter confusion; and the law directs us to praise God the Creator (Demiurgum), and to serve Him alone. Since this is the case, we must not seek for another Father besides Him, or above Him, since there is one God who justifies the circumcision by faith, and the uncircumcision through faith. For if there were any other perfect Father above Him, He (Christ) would by no means have overthrown Satan by means of His words and commandments. For one ignorance cannot be done away with by means of another ignorance, any more than one defect by another defect. If, therefore, the law is due to ignorance and defect, how could the statements contained therein bring to nought the ignorance of the devil, and conquer the strong man? For a strong man can be conquered neither by an inferior nor by an equal, but by one possessed of greater power. But the Word of God is the superior above all, He who is loudly proclaimed in the law: “Hear, O Israel, the Lord your God is one God;” and, “You shall love the Lord your God with all your heart;” and, “Him shall you adore, and Him alone shall you serve.” Then in the Gospel, casting down the apostasy by means of these expressions, He did both overcome the strong man by His Father's voice, and He acknowledges the commandment of the law to express His own sentiments, when He says, “You shall not tempt the Lord your God.” For He did not confound the adversary by the saying of any other, but by that belonging to His own Father, and thus overcame the strong man.
2. He taught by His commandment that we who have been set free should, when hungry, take that food which is given by God; and that, when placed in the exalted position of every grace [that can be received], we should not, either by trusting to works of righteousness, or when adorned with super-eminent [gifts of] ministration, by any means be lifted up with pride, nor should we tempt God, but should feel humility in all things, and have ready to hand [this saying], “You shall not tempt the Lord your God.” As also the apostle taught, saying, “Minding not high things, but consenting to things of low estate;” that we should neither be ensnared with riches, nor mundane glory, nor present fancy, but should know that we must “worship the Lord your God, and serve Him alone,” and give no heed to him who falsely promised things not his own, when he said, “All these will I give you, if, falling down, you will worship me.” For he himself confesses that to adore him, and to do his will, is to fall from the glory of God. And in what thing either pleasant or good can that man who has fallen participate? Or what else can such a person hope for or expect, except death? For death is next neighbour to him who has fallen. Hence also it follows that he will not give what he has promised. For how can he make grants to him who has fallen? Moreover, since God rules over men and him too, and without the will of our Father in heaven not even a sparrow falls to the ground, it follows that his declaration, “All these things are delivered unto me, and to whomsoever I will I give them,” proceeds from him when puffed up with pride. For the creation is not subjected to his power, since indeed he is himself but one among created things. Nor shall he give away the rule over men to men; but both all other things, and all human affairs, are arranged according to God the Father's disposal. Besides, the Lord declares that “the devil is a liar from the beginning, and the truth is not in him.” If then he be a liar and the truth be not in him, he certainly did not speak truth, but a lie, when he said, “For all these things are delivered to me, and to whomsoever I will I give them.”
Source: Adversus haereses (New Advent)