So long as the Church had no New Testament the Old Testament was always in danger so far as its recognition by the Church as an authoritative book was concerned, indeed was in peril of life in the Church. Almost all |heretics| of the second century rejected it, and this of itself shows how difficult it was for many Gentile Christians to sympathise with it. On the other hand, so long as the Old Testament dominated the Church as the sole litera scripta the danger was always present that the Christian Religion would not shake itself free of the shell of Judaism, or, in other words, would not be able to give forceful expression to that in itself which transcended Judaism. Once, however, the New Testament was there, both dangers were exorcised with one stroke. The ancient conception of |the New Covenant| carried over into a canon of |the books of the New Covenant| had simultaneous effect to the right and the left, and definitely removed the chief difficulties in either direction. Henceforth Jewish Christians became heretics because they had no New Testament -- Iren√¶us already includes them in his catalogue of heretics -- and the chief weapon of the heretics in their conflict with the Church and the Old Testament, the weapon which they possessed in their collections of Christian books, was now snatched from their hand.
Though the books of the New Testament were now established as a second Canon side by side with the Old Testament, it was impossible that this arrangement should produce equality of rank in the two Canons. The new Covenant, indeed, would have been quite superfluous if the old Covenant had been perfect; accordingly the new Canon would also have been quite superfluous if the Scriptures of the Old Testament had been sufficient. The new Canon by being attached to the old Canon acquired all the lofty predicates and attributes as well as the whole apparatus of interpretation of the old Bible, and equipped with these extraordinary advantages at once thrust the old Canon into an inferior position. In Justin there is as yet no trace of such subordination, for at his time there was no New Testament; but thirty years after-wards in Ire√¶eus it is obvious: |The books of the Old Testament are the books of the legisdatio in servitutem, the books of the New Testament are the books of the legisdatio in libertatem| (vide supra, p.40). The former books belong to the childhood of mankind. This idea is developed by Tertullian, and comes to complete and most powerful expression in his remarks on the text: |The Law and the Prophets were until John.| At last St Paul's fundamental conception could come to its own in the Church, whereas earlier it seemed to lead into the abysses of Gnosticism: the Law is abolished through fulfilment, it is |demutatum et suppletum.| Now it could be without danger declared that the Apostles stand on a higher plane than the Prophets of the Old Testament -- Novatian has expressed this thought most powerfully. The Christian can live from the New Testament alone, but not from the Old Testament alone.
This position, however, involved a multitude of paradoxes; for the Christian must henceforth regard the Old Testament at one and the same time in the following four ways: (1) The Book is the work of the Holy Spirit, and as such of absolute authority; (2) The Book is in every line of it the book of prophecy, and is so far limited in that it does not contain the fulfilment; (3) the Book is the fundamental document of the legisdatio in servitutem, and as such is transcended and antiquated by the New Testament; (4) the Book is in every line full of mystic symbols of the truth, and these are present even in those passages which because they contain ceremonial ordinances are abolished. The inevitable result was that the different parts of the book were divided under these points of view though without any recognised principle of division. The story of Creation in six days for instance, as told in Genesis, was always regarded in the Church as a record of absolute and most glorious truth that had been in no sense altered or added to by the New Testament. Much else in the Old Testament remained for the Church on the very highest level of authority. Other parts, however, were subject to a more depreciatory or a doubtful verdict. Slowly, and yet from the very first, the New Testament thrust the Old Testament into the background, and even in the public services of the Church claimed and obtained precedence. The juxtaposition of the Old Testament and New Testament gave rise to investigations concerning the nature of Christianity of which otherwise no one would have thought, and taught a better understanding of the nature of the new religion, as we see at once when we compare the expositions of the early Catholic Fathers with those of the Apologists. how superior are Iren√¶us and Tertullian to Justin in their knowledge of the nature of Christianity! How far superior is Clement of Alexandria! And even if the advance noticeable in the works of Clement is in great part due to his philosophy, still he also owes much to the four Gospels and, above all, to the Pauline Epistles. Lastly, the fact that the Canon of Scripture contained in the Old Testament something that was |relative| was of great importance. The numbing influence of Biblicism, otherwise inevitable, was thus warded off. That the Christian religion did not become a religion of |the book| in the full sense of the word is due, next to the fact that the |Rule of Faith| had authority side by side with the Bible, to the fact that in the Bible itself there was this tension between the Old Testament and New Testament. The inconsistency and inconvenience of having in the sacred Oracles of God elements of graduated, indeed sometimes antiquated, value were undoubtedly fraught with good. The New Testament has secured the continuance of the Old Testament in the Church, and at the same time has guarded against the stunting effect of its Judaism, just because the Old Testament was thrust into an inferior position by the New Testament. Moreover, the way to the historical treatment of the two Testaments was thus left open for future ages. Tentative beginnings of such treatment already manifest themselves in Iren√¶us and Clement, who here follow St Paul. But they would not have been able to follow St Paul if collections of epistles of the Apostle had not been already in existence, equipped with an authority to which they could appeal.