Why does the Christian Bible contain someone else’s scriptures?

Around 144, in Rome, a teacher named Marcion broke with the church over his claim that the God of the Hebrew scriptures was not the Father of Jesus. Irenaeus, writing a few decades later, reports that he "mutilates the Gospel which is according to Luke", cut the passages where Jesus calls the creator his Father, and removed from Paul’s letters the passages where Paul quotes the prophets as announcing the coming of the Lord.

He produced, in effect, the first Christian canon, and it was a short one. The church rejected it, and in rejecting it committed to keeping a library that made its own position harder rather than easier.

The New Testament quotes the Hebrew scriptures constantly, and often as pointing forward. Passages about a suffering servant, a coming king, a new covenant, are applied to Jesus, often directly and without argument, as though the application were obvious. Paul is different: as Richard Hays has argued, few of his quotations are applied directly to Christ, and most to the church.

Paul, who is a Jew writing about this, is not simple about it. He spends three chapters of Romans on the question of what has happened to Israel. He says that some branches were broken off, and he also says that "God didn’t reject his people, whom he foreknew", and that "the gifts and the calling of God are irrevocable."

The Hebrew Bible is a complete scripture in Judaism, twenty-four books read through a rabbinic tradition of its own, and the passages Christians read as predictions of Jesus are read there in their own contexts, about their own subjects, and where one is read of the Messiah, of a messiah still awaited. Rashi, the eleventh-century commentator whose notes stand beside the text in almost every Jewish edition, reads the servant who suffers in Isaiah 53 as Israel, which the prophet speaks of "as one man".

This is a genuine interpretative disagreement between two traditions, not one tradition missing something. Dabru Emet, a statement signed in 2000 by more than 170 rabbis and Jewish intellectuals, says that Jews and Christians "interpret the Bible differently on many points. Such differences must always be respected."

Christian traditions have not agreed on this, and several have changed their minds. The range runs from reading God’s covenant with Israel as fulfilled and therefore superseded, through reading it as still in force alongside a second one, to reading it as one covenant all along with the membership widened. The first, supersession, was the standard view by the Middle Ages. A Vatican commission wrote in 2015 that a supersession theology setting "a Church of the Gentiles and the rejected Synagogue" against each other "is deprived of its foundations", and that God’s covenant with Israel "has never been revoked". The Presbyterian Church (U.S.A.) had said in 1987 that "Christians have not replaced Jews."

The question is not academic. It determines whether Judaism is a religion that ended, a religion that continues, or the root of the thing doing the asking, and different churches have answered all three ways at different times.

Read without the New Testament, these books are not an introduction to anything. They are a national literature: law, prophecy, history, psalms and proverbs, assembled over centuries.

Reading them that way produces conclusions about what a passage meant to its own audience that differ from what it came to mean later. Both meanings are real and they are not the same object.

The parting of Judaism and Christianity took place over generations, and scholars now dispute whether the ways ever finally parted at all. When it became impossible to be both, what the people in the middle thought, and how many of them there were, is not recoverable.

A reading in which one people’s scriptures belong properly to somebody else has a history, and it is not a neutral one. The charge that the Jewish people collectively bore guilt for the crucifixion was made for centuries and used to justify what followed from it.

In 1965 the Second Vatican Council addressed this directly. It grants the older claim that "the Jewish authorities and those who followed their lead pressed for the death of Christ" and then refuses the inference from it: "what happened in His passion cannot be charged against all the Jews, without distinction, then alive, nor against the Jews of today". It still calls the Church "the new people of God", and says in the same sentence that the Jews "should not be presented as rejected or accursed by God, as if this followed from the Holy Scriptures"; and the church "decries hatred, persecutions, displays of anti-Semitism, directed against Jews at any time and by anyone".

That a council had to say it in 1965 is the part worth sitting with.

Christianity holds that the God of Israel and the Father of Jesus are one God, which is the proposition Marcion denied and the reason the library stayed. Without it Jesus is a teacher who arrived from nowhere, and the tradition has consistently judged that too high a price for a tidier book.

It is a costly choice and it was made deliberately. The church could have had a scripture with no awkward inheritance, no arguments about what a prophet meant, and no other people already reading it. It declined.