From the Thirty-Ninth Festal Letter, for Easter 367: The Books of Scripture

… They have made up books they call books of tables, in which they show stars and give them the names of saints. And in doing so they have truly brought a double disgrace on themselves. The writers of such books are disgraced because they have made themselves experts in a lying and contemptible science. And as for the ignorant and simple, they have led them astray by evil thoughts about the right faith, which is established in all truth and upright in the presence of God. … But we have spoken of the heretics as dead, and of ourselves as possessing the divine Scriptures for salvation. And I am afraid that, as Paul wrote to the Corinthians, a few of the simple may be led astray from their simplicity and purity by the cunning of certain people, and may from then on read other books, the ones called apocryphal, misled by the likeness of their names to the true books. So I urge you to bear with me if I too write, by way of reminder, about matters you already know, moved by the need and benefit of the church. [a]

In going on to speak of these things, I will take the pattern of Luke the evangelist to commend my undertaking, and say on my own account: “Since some have undertaken” to arrange for themselves the books called apocryphal and to mix them with the divinely inspired Scripture, of which we have been fully persuaded, just as those who from the beginning were eyewitnesses and ministers of the Word handed it down to the fathers, it seemed good to me also, having been urged to it by true brothers, and having learned from the beginning, to set before you the books that are included in the canon, handed down, and accepted as divine. In this way anyone who has fallen into error may condemn those who led him astray, and anyone who has remained steadfast in purity may rejoice again at being reminded of these things. [e]

There are, then, twenty-two books of the Old Testament in number. For, as I have heard, it has been handed down that this is the number of the letters of the Hebrew alphabet. Their order and names are as follows. The first is Genesis, then Exodus, next Leviticus, after that Numbers, and then Deuteronomy. After these comes Joshua the son of Nun, then Judges, then Ruth. And again, after these, the four books of Kings, the first and second being counted as one book, and likewise the third and fourth as one book. And again, the first and second of the Chronicles are counted as one book. Again, Ezra, the first and second, are likewise one book. After these there is the book of Psalms, then the Proverbs, next Ecclesiastes, and the Song of Songs. Job follows, then the Prophets, the twelve being counted as one book. Then Isaiah, one book; then Jeremiah with Baruch, Lamentations, and the letter, one book; after that, Ezekiel and Daniel, each one book. This makes up the Old Testament. [f]

Again, it is not tiresome to speak of the books of the New Testament. They are these: the four Gospels, according to Matthew, Mark, Luke, and John. After them, the Acts of the Apostles, and the letters called catholic, seven in number, namely: of James, one; of Peter, two; of John, three; after these, one of Jude. Besides these there are fourteen letters of Paul, written in this order: the first, to the Romans; then two to the Corinthians; after these, to the Galatians; next, to the Ephesians; then to the Philippians; then to the Colossians; after these, two to the Thessalonians, and the one to the Hebrews; and again, two to Timothy; one to Titus; and last, the one to Philemon. And besides these, the Revelation of John. [g]

These are the fountains of salvation, so that those who thirst may be satisfied with the living words they contain. In these alone the teaching of godliness is proclaimed. Let no one add to them, and let no one take anything away from them. For it was about these that the Lord put the Sadducees to shame when he said, “You are in error, because you do not know the Scriptures.” And he rebuked the Jews, saying, “Search the Scriptures, for it is they that testify about me.” [h]

But for greater exactness I add this as well, writing because I must. There are other books besides these, not included in the canon, but appointed by the fathers to be read by those who are newly joining us and who want to be instructed in the word of godliness: the Wisdom of Solomon, the Wisdom of Sirach, Esther, Judith, Tobit, the book called the Teaching of the Apostles, and the Shepherd. But the former books, my brothers and sisters, are included in the canon, while the latter are only read. And nowhere is there any mention of apocryphal writings. They are an invention of heretics, who write them whenever they like, give them their own approval, and assign them dates, so that by passing them off as ancient writings they may find a way to lead the simple astray. [i]