1 They (the Jews) had therefore a law, a course of discipline, and a prophecy of future things. For God at the first, indeed, warning them by means of natural precepts, which from the beginning He had implanted in mankind, that is, by means of the Decalogue (which, if any one does not observe, he has no salvation), did then demand nothing more of them. As Moses says in Deuteronomy, “These are all the words which the Lord spoke to the whole assembly of the sons of Israel on the mount, and He added no more; and He wrote them on two tables of stone, and gave them to me.” For this reason [He did so], that they who are willing to follow Him might keep these commandments. But when they turned themselves to make a calf, and had gone back in their minds to Egypt, desiring to be slaves instead of free-men, they were placed for the future in a state of servitude suited to their wish—[a slavery] which did not indeed cut them off from God, but subjected them to the yoke of bondage; as Ezekiel the prophet, when stating the reasons for the giving of such a law, declares: “And their eyes were after the desire of their heart; and I gave them statutes that were not good, and judgments in which they shall not live.” Luke also has recorded that Stephen, who was the first elected into the diaconate by the apostles, and who was the first slain for the testimony of Christ, spoke regarding Moses as follows: “This man did indeed receive the commandments of the living God to give to us, whom your fathers would not obey, but thrust [Him from them], and in their hearts turned back again into Egypt, saying unto Aaron, Make us gods to go before us; for we do not know what has happened to [this] Moses, who led us from the land of Egypt. And they made a calf in those days, and offered sacrifices to the idol, and were rejoicing in the works of their own hands. But God turned, and gave them up to worship the hosts of heaven; as it is written in the book of the prophets: O you house of Israel, have you offered to Me sacrifices and oblations for forty years in the wilderness? And you took up the tabernacle of Moloch, and the star of the god Remphan, figures which you made to worship them;” pointing out plainly, that the law being such, was not given to them by another God, but that, adapted to their condition of servitude, [it originated] from the very same [God as we worship]. Wherefore also He says to Moses in Exodus: “I will send forth My angel before you; for I will not go up with you, because you are a stiff-necked people.”
2. And not only so, but the Lord also showed that certain precepts were enacted for them by Moses, on account of their hardness [of heart], and because of their unwillingness to be obedient, when, on their saying to Him, “Why then did Moses command to give a writing of divorcement, and to send away a wife?” He said to them, “Because of the hardness of your hearts he permitted these things to you; but from the beginning it was not so;” thus exculpating Moses as a faithful servant, but acknowledging one God, who from the beginning made male and female, and reproving them as hard-hearted and disobedient. And therefore it was that they received from Moses this law of divorcement, adapted to their hard nature. But why say I these things concerning the Old Testament? For in the New also are the apostles found doing this very thing, on the ground which has been mentioned, Paul plainly declaring, “But these things I say, not the Lord.” And again: “But this I speak by permission, not by commandment.” And again: “Now, as concerning virgins, I have no commandment from the Lord; yet I give my judgment, as one that has obtained mercy of the Lord to be faithful.” But further, in another place he says: “That Satan tempt you not for your incontinence.” If, therefore, even in the New Testament, the apostles are found granting certain precepts in consideration of human infirmity, because of the incontinence of some, lest such persons, having grown obdurate, and despairing altogether of their salvation, should become apostates from God—it ought not to be wondered at, if also in the Old Testament the same God permitted similar indulgences for the benefit of His people, drawing them on by means of the ordinances already mentioned, so that they might obtain the gift of salvation through them, while they obeyed the Decalogue, and being restrained by Him, should not revert to idolatry, nor apostatize from God, but learn to love Him with the whole heart. And if certain persons, because of the disobedient and ruined Israelites, do assert that the giver (doctor) of the law was limited in power, they will find in our dispensation, that “many are called, but few chosen;” and that there are those who inwardly are wolves, yet wear sheep's clothing in the eyes of the world (foris); and that God has always preserved freedom, and the power of self-government in man, while at the same time He issued His own exhortations, in order that those who do not obey Him should be righteously judged (condemned) because they have not obeyed Him; and that those who have obeyed and believed on Him should be honoured with immortality.
Source: Adversus haereses (New Advent)