What Is the Difference Between the Old and New Testament?

What "testament" means

The word is a translation accident that stuck. The Latin testamentum rendered the Greek diatheke, which in the Bible means covenant — a binding agreement between God and a people. The Old Testament centres on the covenant made with Israel at Sinai, with its law; the New centres on the "new covenant" Jeremiah 31 had promised and that Jesus, at the last supper, said his death established. So the names are not "old book" and "new book" but "the writings of the first covenant" and "the writings of the second."

Side by side

The basic facts, before the relationship between them:

What the Old Testament contains

Four kinds of book. The Law (Genesis to Deuteronomy) tells of creation, the patriarchs, the exodus and the covenant at Sinai, and contains the laws given there. The History books (Joshua to Esther) follow Israel into the land, through kings and civil war, into exile and back. The Poetry and Wisdom books (Job to Song of Solomon) are prayers, songs and reflections — the Psalms are Israel's hymnbook. The Prophets (Isaiah to Malachi) are God's messengers to a people who kept breaking the covenant, warning of judgment and promising restoration.

For Jews this collection, in a different order, is the whole Bible. Jesus and every New Testament writer knew it as "the Scriptures" and quoted it constantly — around three hundred direct quotations and many more allusions.

What the New Testament contains

Four Gospels tell the life, death and resurrection of Jesus from four angles. Acts continues the story for thirty years as the movement spreads from Jerusalem to Rome. Twenty-one letters — thirteen under Paul's name, eight by others — teach and correct the young churches. Revelation closes the collection with a vision addressed to seven churches under pressure.

It is short. The whole New Testament is roughly the length of a modern novel and can be read aloud in about sixteen hours.

How the two relate

Christians have always read them as one story in two acts, not as two religions. The New Testament's own claim is continuity: Jesus said he came "not to abolish the Law or the Prophets but to fulfil them" (Matthew 5:17); Matthew's Gospel opens with a genealogy tying him to Abraham and David; Paul argues from Genesis and Habakkuk; Hebrews reads the whole Old Testament sacrificial system as a sketch of what Jesus did. The Old Testament sets the problem, the promises and the categories — covenant, sacrifice, kingdom, Messiah — and the New says they have been kept.

This is why the Old Testament is three-quarters of a Christian Bible rather than an appendix. The New Testament is nearly unreadable without it: Revelation alone has several hundred Old Testament allusions, and "Christ" is simply the Greek for the Hebrew "Messiah," a title that only means anything against the background of the Psalms and Isaiah.

Common misunderstandings

Three ideas circulate widely and none survives reading both halves:

• "The Old Testament God is angry, the New Testament God is loving." The Old Testament's most repeated description of God is "merciful and gracious, slow to anger, abounding in steadfast love" (Exodus 34:6, quoted a dozen times after). The New Testament has Jesus speaking of judgment more than anyone else in it. The same God, and the same range, in both.
• "Christians don't follow the Old Testament." Christians read it as Scripture and keep its moral core; what the New Testament sets aside is the ceremonial law — sacrifices, food laws, circumcision — on the grounds that Jesus fulfilled what those pointed to. Working out which is which occupies Acts 15, Galatians and much of Romans.
• "The Old Testament is history and the New Testament is theology." Both have both. Leviticus is theology; Acts is history. The difference is subject and period, not kind.

Which to read first

For a first reader: a Gospel, then come back. The Old Testament assumes nothing but is long and its hardest stretches come early; the New assumes the Old but its opening books are self-contained stories. Most people do best reading Mark or John, then Genesis and Exodus, then the rest of the New Testament, and only then a full pass through the Old — by which point they know what it is building toward.