1 All things therefore are of one and the same substance, that is, from one and the same God; as also the Lord says to the disciples “Therefore every scribe, which is instructed unto the kingdom of heaven, is like a man that is an householder, which brings forth out of his treasure things new and old.” He did not teach that he who brought forth the old was one, and he that brought forth the new, another; but that they were one and the same. For the Lord is the good man of the house, who rules the entire house of His Father; and who delivers a law suited both for slaves and those who are as yet undisciplined; and gives fitting precepts to those that are free, and have been justified by faith, as well as throws His own inheritance open to those that are sons. And He called His disciples “scribes” and “teachers of the kingdom of heaven;” of whom also He elsewhere says to the Jews: “Behold, I send unto you wise men, and scribes, and teachers; and some of them you shall kill, and persecute from city to city.” Now, without contradiction, He means by those things which are brought forth from the treasure new and old, the two covenants; the old, that giving of the law which took place formerly; and He points out as the new, that manner of life required by the Gospel, of which David says, “Sing unto the Lord a new song;” and Esaias, “Sing unto the Lord a new hymn. His beginning (initium), His name is glorified from the height of the earth: they declare His powers in the isles.” And Jeremiah says: “Behold, I will make a new covenant, not as I made with your fathers” in Mount Horeb. But one and the same householder produced both covenants, the Word of God, our Lord Jesus Christ, who spoke with both Abraham and Moses, and who has restored us anew to liberty, and has multiplied that grace which is from Himself.
2. He declares: “For in this place is One greater than the temple.” But [the words] greater and less are not applied to those things which have nothing in common between themselves, and are of an opposite nature, and mutually repugnant; but are used in the case of those of the same substance, and which possess properties in common, but merely differ in number and size; such as water from water, and light from light, and grace from grace. Greater, therefore, is that legislation which has been given in order to liberty than that given in order to bondage; and therefore it has also been diffused, not throughout one nation [only], but over the whole world. For one and the same Lord, who is greater than the temple, greater than Solomon, and greater than Jonah, confers gifts upon men, that is, His own presence, and the resurrection from the dead; but He does not change God, nor proclaim another Father, but that very same one, who always has more to measure out to those of His household. And as their love towards God increases, He bestows more and greater [gifts]; as also the Lord said to His disciples: “You shall see greater things than these.” And Paul declares: “Not that I have already attained, or that I am justified, or already have been made perfect. For we know in part, and we prophesy in part; but when that which is perfect has come, the things which are in part shall be done away.” As, therefore, when that which is perfect has come, we shall not see another Father, but Him whom we now desire to see (for “blessed are the pure in heart: for they shall see God”); neither shall we look for another Christ and Son of God, but Him who [was born] of the Virgin Mary, who also suffered, in whom too we trust, and whom we love; as Esaias says: “And they shall say in that day, Behold our Lord God, in whom we have trusted, and we have rejoiced in our salvation;” and Peter says in his Epistle: “Whom, not seeing, you love; in whom, though now you see Him not, you have believed, you shall rejoice with joy unspeakable;” neither do we receive another Holy Spirit, besides Him who is with us, and who cries, “Abba, Father;” and we shall make increase in the very same things [as now], and shall make progress, so that no longer through a glass, or by means of enigmas, but face to face, we shall enjoy the gifts of God—so also now, receiving more than the temple, and more than Solomon, that is, the advent of the Son of God, we have not been taught another God besides the Framer and the Maker of all, who has been pointed out to us from the beginning; nor another Christ, the Son of God, besides Him who was foretold by the prophets.
3. For the new covenant having been known and preached by the prophets, He who was to carry it out according to the good pleasure of the Father was also preached, having been revealed to men as God pleased; that they might always make progress through believing in Him, and by means of the [successive] covenants, should gradually attain to perfect salvation. For there is one salvation and one God; but the precepts which form the man are numerous, and the steps which lead man to God are not a few. It is allowable for an earthly and temporal king, though he is [but] a man, to grant to his subjects greater advantages at times: shall not this then be lawful for God, since He is [ever] the same, and is always willing to confer a greater [degree of] grace upon the human race, and to honour continually with many gifts those who please Him? But if this be to make progress, [namely,] to find out another Father besides Him who was preached from the beginning; and again, besides him who is imagined to have been discovered in the second place, to find out a third other, — then the progress of this man will consist in his also proceeding from a third to a fourth; and from this, again, to another and another: and thus he who thinks that he is always making progress of such a kind, will never rest in one God. For, being driven away from Him who truly is [God], and being turned backwards, he shall be for ever seeking, yet shall never find out God; but shall continually swim in an abyss without limits, unless, being converted by repentance, he return to the place from which he had been cast out, confessing one God, the Father, the Creator, and believing [in Him] who was declared by the law and the prophets, who was borne witness to by Christ, as He did Himself declare to those who were accusing His disciples of not observing the tradition of the elders: “Why do you make void the law of God by reason of your tradition? For God said, Honour your father and mother; and, Whosoever curses father or mother, let him die the death.” And again, He says to them a second time: “And you have made void the word of God by reason of your tradition;” Christ confessing in the plainest manner Him to be Father and God, who said in the law, “Honour your father and mother; that it may be well with you.” For the true God did confess the commandment of the law as the word of God, and called no one else God besides His own Father.
Source: Adversus haereses (New Advent)