The faith of the NT is under-girded by constant references to the OT—250 direct quotations and many more allusions. It was important to maintain the continuity of the new covenant with the old and to justify the Christians' claim to their having superseded the Jews as a chosen people. The OT is usually quoted in the LXX version and without any necessary relationship to the historical context of the original. Such quotations are especially frequent in Matthew; thus the infancy narratives are set in a context of fulfilment: Hosea had once mentioned how God had called his ‘son’ (Israel) out of Egypt at the Exodus (Hos. 11: 1, quoted by Matt., unusually, from the Hebrew), and when Jesus was taken as a refugee to Egypt and brought back (Matt. 2: 21) this was a fulfilment of prophecy. The OT story of Exodus, crossing the water, wanderings for forty years in the wilderness, and the giving of the Law at Sinai is understood typologically in the gospels. What happened to Israel, which was a disobedient people, happens by contrast to Jesus, who is obedient, and so God's plan is fulfilled. There are therefore many OT allusions and quotations in Matthew, including one difficult to recognize (Matt. 2: 23), and in the other gospels.

Paul's many quotations from the OT are usually from the LXX text. Sometimes they are quoted because the words are required in a straightforward literal sense (Rom. 3: 10–17) and sometimes he adapts an OT text to a subject to which it bears no obvious relation (1 Cor. 9: 9). Other OT quotations are used typologically. See old testament in the new testament.