To properly interpret the New Testament, knowledge of the Judaism of this period is often necessary
The New Testament recognises the divine authority of the Jewish Scriptures and supports itself on this authority. When the New Testament speaks of the “Scriptures” and refers to “that which is written”, it is to the Jewish Scriptures that it refers. It affirms that these Scriptures must of necessity be fulfilled, since they define God’s plan which cannot fail to be realised, notwithstanding the obstacles encountered and the human resistance opposing it. To that the New Testament adds that these Scriptures are indeed fulfilled in the life of Jesus, his Passion and resurrection, as well as in the foundation of the Church that is open to all the nations. All of these bind Christians and Jews closely together, for the foremost aspect of scriptural fulfilment is that of accord and continuity. This is fundamental. Inevitably, fulfilment brings discontinuity on certain points, because without it there can be no progress. This discontinuity is a source of disagreements between Christians and Jews, no purpose is served by hiding the fact.
This continuity has deep roots and manifests itself at many levels. That is why in Christianity the link between Scripture and Tradition is similar to that in Judaism. Jewish methods of exegesis are frequently employed in the New Testament. The Christian canon of the Old Testament owes its formation to the first century Jewish Scriptures.
But it was wrong, in times past, to unilaterally insist on it to the extent of taking no account of the fundamental continuity
85. But it is especially in studying the great themes of the Old Testament and their continuation in the New which accounts for the impressive symbiosis that unites the two parts of the Christian Bible and, at the same time, the vigorous spiritual ties that unite the Church of Christ to the Jewish people. In both Testaments, it is the same God who enters into relationship with human beings and invites them to live in communion with him; the one God and the source of unity; God the Creator who continues to provide for the needs of his creatures, in particular those who are intelligent and free, and who are called to recognise the truth and to love; God especially is the Liberator and Saviour of human beings, because, although created in his image, they have fallen through sin into a pitiful slavery.
It is impossible to discover what that plan is by philosophical speculation on the human being in general. God reveals this plan by unforeseeable initiatives, in particular, by the call addressed to an individual chosen from all the rest of humanity, Abraham (Gn 12:1-3), and by guiding the destiny of this person and his posterity, the people of Israel (Ex 3:10). A central Old Testament theme (Dt 7:6-8), Israel’s election continues to be of fundamental importance in the New Testament. Far from calling it into question, the birth of Jesus confirms it in the most spectacular manner. Jesus is “son of David, son of Abraham” (Mt 1:1). He comes “to save his people from their sins” (1:21). He is the Messiah promised to Israel (Jn 1:41,45); he is “the Word” (Logos) come “to his own” (Jn 1:11-14). The salvation he brings through his paschal mystery is offered first of all to the Israelites. 345 As foreseen by the Old Testament, this salvation has universal repercussions as well. 346 It is also offered to the Gentiles. Moreover, it is accepted by many of them, to the extent that they have become the great majority of Christ’s disciples. But Christians from the nations profit from salvation only by being introduced, by their faith in Israel’s Messiah, into the posterity of Abraham (Ga 3:7,29). Many Christians from the “nations” are not aware that they are by nature “wild olives” and that their faith in Christ has grafted them onto the olive tree chosen by God (Rm -18).