Why Catholics and Protestants Have Different Old Testaments

Catholics and Protestants open the same New Testament and confess the same Lord Jesus Christ. We read the same Gospels, hear the same apostolic witness, and proclaim the same central mystery: Christ has died, Christ is risen, Christ will come again. Yet when we turn to the Old Testament, our Bibles are not identical. That difference matters, but it should not become a weapon. It should become an invitation to read more carefully, more historically, and more faithfully within the life of the Church.

The Catholic Bible contains 73 books: 46 in the Old Testament and 27 in the New Testament. Most Protestant Bibles contain 66 books: 39 in the Old Testament and the same 27 in the New Testament. The difference lies in a group of Old Testament writings Catholics call the deuterocanonical books: Tobit, Judith, Wisdom, Sirach, Baruch, First and Second Maccabees, along with additional passages in Esther and Daniel. Protestants often call these books the Apocrypha and usually do not receive them as Scripture in the same way.

This difference did not appear because one side loved the Bible and the other did not. It comes from a long and complicated history of how the people of God received, copied, prayed, translated, and handed on the Scriptures.

Many early Christians used the Greek translation of the Old Testament known as the Septuagint. This was the Bible of many Greek-speaking Jews before and during the time of Christ, and it was widely used in the early Church from the apostolic age. The Septuagint included the books Catholics now call deuterocanonical. The New Testament authors often quote the Old Testament in forms that resemble the Septuagint, showing how deeply this Greek biblical tradition shaped the earliest Christian imagination.

Later, many Jewish communities came to emphasize the Hebrew collection of Scriptures, which corresponds more closely to the Old Testament found in Protestant Bibles. During the Reformation, Protestant reformers generally followed that Hebrew canon for the Old Testament, while retaining the 27 books of the New Testament. The Catholic Church, especially at the Council of Trent, reaffirmed the broader canon that had been received and used in the Church’s liturgy, teaching, and prayer.

This is important because Catholics are sometimes accused of having “added books” to the Bible. Historically, the picture is different. The broader Old Testament canon was part of the biblical tradition used by Christians for centuries before the Reformation. The Bible printed by Gutenberg in the 1450s, more than half a century before Martin Luther’s break with Rome, was the Latin Vulgate, the Bible of the Western Catholic Church, and it included the deuterocanonical books. In other words, the Catholic Church did not invent a new Bible in response to Protestantism. The canon Catholics receive today is substantially continuous with the Scriptures long read, copied, preached, and prayed in the Church.

St. Augustine stands in an important place in this history. He received the broader Old Testament canon and supported the books that Catholics continue to include today. In the councils of Hippo and Carthage, where Augustine’s influence was significant, the Church listed the Scriptures in a form that substantially matches the Catholic canon. Augustine did not treat the Bible as a private possession to be rearranged according to personal preference. For him, Scripture belonged to the Church because it was given to the Church by God, preserved in the Church’s worship, and interpreted within the Church’s faith.

But Augustine’s importance is not only about the list of biblical books. He also teaches us how to read them.

One of Augustine’s most famous insights is that the New Testament is hidden in the Old, and the Old Testament is unveiled in the New. In other words, the Bible is not a random library of religious texts. It is a unified story that reaches its fullness in Jesus Christ. The Old Testament prepares, promises, foreshadows, warns, sings, and groans toward Him. The New Testament reveals Him as the fulfillment of the Law, the Prophets, and the Psalms.

This is not a clever Christian trick imposed on the Scriptures after the fact. It is the way Jesus Himself taught His disciples to read. After the Resurrection, on the road to Emmaus, Christ opened the Scriptures and showed how Moses and the prophets spoke of Him. He told His disciples that everything written about Him in the Law of Moses, the Prophets, and the Psalms had to be fulfilled. In John’s Gospel, He says, “You search the Scriptures, because you think you have eternal life through them; even they testify on my behalf.”

For the Church, then, the Bible is centered on Christ because Christ says it is. He is not merely one theme among many. He is the key that opens the whole house. At the Last Supper, He identified His own blood as the blood of the new covenant, showing that the promises of God reach their fulfillment in His self-giving love.

This matters especially when we read the Old Testament. We cannot choose an Old Testament passage, pull it out of its place in salvation history, and use it to make whatever point we already wanted to make. We cannot grab a command, a battle, a punishment, a purity law, or a prophetic judgment and treat it as though Christ has not come. The Christian reading of the Old Testament must always pass through the person of Jesus: His Incarnation, His teaching, His Cross, His Resurrection, His mercy, His justice, and His command to love God and neighbor.

This does not mean we reject the Old Testament. That would be an ancient error, not Christian faith. The God of Abraham, Isaac, and Jacob is the Father of our Lord Jesus Christ. The Old Testament is inspired Scripture. It reveals creation, covenant, sin, sacrifice, wisdom, exile, hope, and promise. It teaches us how long God has loved His people and how patiently He has prepared the world for redemption.

But fulfillment changes how we read. A seed is not false because it becomes a tree. A promise is not discarded because it is fulfilled. The Old Testament is true, but Christians read its truth in the light of Christ.

This is why the Church has never treated Scripture as a flat text where every verse functions in the same way. The Church reads according to the literal sense, seeking what the sacred author intended in the historical and literary context. But she also reads according to the spiritual sense, because the same Holy Spirit who inspired the human authors was guiding all of salvation history toward Christ.

The Church sees Adam as a figure of Christ, the new Adam. She sees the Passover lamb fulfilled in the Lamb of God. She sees the crossing of the Red Sea as a sign of baptism. She sees manna in the wilderness as a foreshadowing of the Eucharist. She sees the temple fulfilled in Christ’s body and then in His Church. She sees the suffering servant fulfilled in the crucified Lord. This is not fantasy. It is typology: the pattern of God’s action across history.

Augustine also gives us another crucial rule: authentic interpretation must build up love. In On Christian Doctrine, he teaches that if our reading of Scripture does not lead us toward the love of God and the love of neighbor, we have not yet understood it rightly. This is not sentimentalism. It is deeply biblical. Jesus Himself says the whole Law and the Prophets hang on these two commandments.

That rule is urgently needed today. Many people use the Bible to win arguments, defend resentment, justify harshness, or baptize political instincts. Christians can be tempted to search the Old Testament for verses that support anger, exclusion, domination, or vengeance. But we must ask: How does this passage stand before Christ? How is it fulfilled in Him? How does it lead us to the Cross? How does it teach us to love as He loves?

If our reading of Joshua makes us forget Jesus weeping over Jerusalem, we have read poorly. If our reading of the Law makes us forget the mercy shown to sinners, we have read poorly. If our reading of the prophets makes us thunder against others while refusing repentance ourselves, we have read poorly. If our reading of divine judgment makes us delight in condemnation rather than hunger for conversion, we have read poorly.

The Catholic and Protestant difference over the Old Testament canon is real, and it should be discussed honestly. Catholics receive the deuterocanonical books as inspired Scripture, part of the Church’s Bible. Protestants generally value them historically or devotionally, but do not give them the same authority. That distinction affects doctrine, liturgy, and spiritual reading. For example, Catholic teaching often draws from books such as Wisdom, Sirach, and Maccabees in ways Protestant traditions do not.

Yet beneath that difference, Christians must still face a shared responsibility: we must read the Bible as disciples of Jesus Christ. Whether one is reading Genesis, Isaiah, the Psalms, Wisdom, Romans, or Revelation, the question is never simply, “How can I use this text?” The question is, “How does this text bear witness to Christ, and how must I be converted by Him?”

The Church’s method is not to silence Scripture, but to hear it whole: not one isolated verse against another, not the Old Testament against the New, not law against grace, not justice against mercy, but the entire symphony of revelation brought to its fullness in the Word made flesh.

Jesus Christ is the center because He is the center of history. He is the image of the invisible God. He is the covenant fulfilled. He is the true temple, the true priest, the true sacrifice, the true king, the true prophet, and the true wisdom of God. He is the peace promised by the prophets and the love for which the human heart was made.

So when we open the Old Testament, we should do so with reverence, not suspicion. But we should also do so as Christians, not as though the Resurrection has not happened. Every passage must be weighed in the light of Christ. Every interpretation must kneel before Him. Every moral claim must be tested by His commandment of love. Every hard text must be carried to the Cross.