Old Testament vs. New Testament: How the Two Fit Together

The Old Testament is the story of God’s promises to Israel, written before Jesus. The New Testament is the story of Jesus and the early church, written after him. One sets up the story, the other finishes it. You need both to make sense of either.

The quick comparison

What “testament” means

Testament is an old word for covenant, a binding agreement. The Old Testament centers on the covenant God made with Israel at Mount Sinai. The New Testament centers on what Jesus called the “new covenant” at the Last Supper (Luke 22:20). The prophet Jeremiah had promised one centuries earlier (Jeremiah 31:31).

So the names aren’t “old and outdated” versus “new and improved.” They’re two chapters of one relationship.

What’s in the Old Testament

Five groups of books: the Law (Genesis to Deuteronomy), History (Joshua to Esther), Poetry and Wisdom (Job to Song of Solomon), and the Major and Minor Prophets. It covers creation, Abraham’s family, slavery in Egypt, the Exodus, Israel’s kings, exile in Babylon and the return home. Our Bible timeline walks through it era by era.

What’s in the New Testament

Four Gospels about Jesus, the book of Acts about the early church, 21 letters (13 from Paul, 8 from others), and Revelation. It all happens in about one lifetime, under the Roman Empire.

How the two fit together

Think of it like a mystery novel. The Old Testament lays out the clues: a promise to bless every nation through Abraham’s family, a king from David’s line who’ll reign forever, a suffering servant in Isaiah 53, a new covenant written on hearts. Then it ends without the payoff.

The New Testament claims Jesus is that payoff. Matthew quotes the Old Testament constantly to make the point. And after his resurrection, Jesus walks two confused followers through the Scriptures, starting “at Moses and all the prophets” to explain what they say about him (Luke 24:27).

Read the New Testament without the Old and you miss the setup. Read the Old without the New and the story stops mid-sentence.

Do Christians still follow the Old Testament?

Christians still read and treasure it. Jesus quoted it, and so did every New Testament writer. But most Christians believe some parts, like the sacrifice system and the food laws, were fulfilled in Jesus and no longer apply the same way. The moral heart of the law (love God, love your neighbor) still stands. Different Christian traditions draw those lines a bit differently.

Which one should you read first?

If you’re new, start in the New Testament with Mark. Then go back to Genesis with some context. Our guide on how to read the Bible for beginners lays out a simple order, and the full list of all 66 books shows where everything sits.

FAQ

How many books are in the Old and New Testaments?

39 in the Old Testament and 27 in the New, for 66 total in Protestant Bibles. Catholic Bibles have 46 Old Testament books.

What’s the main difference between the Old and New Testament?

The Old Testament was written before Jesus and focuses on God’s covenant with Israel. The New Testament was written after Jesus and focuses on his life and the early church.

Is the God of the Old Testament different from the God of the New?

Christians believe it’s the same God. You’ll find judgment and mercy in both testaments. Jesus himself describes God’s love and God’s judgment, sometimes in the same breath.

What language was the Bible written in?

The Old Testament was written mostly in Hebrew, with a few sections in Aramaic. The New Testament was written in Greek.

Which testament is longer?

The Old Testament, by a lot. It makes up roughly three-quarters of the Bible.