How many are the canonical books of the Old Testament?
St Cyril of Jerusalem, St Athanasius the Great, and St John of Damascus count the canonical books of the Old Testament as twenty-two, grouping certain books together. This was a symbolic number, corresponding to the twenty-two letters of the Hebrew alphabet (St Cyril of Jerusalem, Catechetical Lectures, 4.33–35; St Athanasius, Festal Letter 39; St John of Damascus, Exact Exposition of the Orthodox Faith, IV.17; see Q003, Q008).
In current practice, these twenty-two grouped books are counted as thirty-nine canonical books, alongside which stand several “deuterocanonical” books, which will be listed and explained below.
All of these books, together with the twenty-seven books of the New Testament, form the corpus of the Bible. All are needed and useful to equip Christians to understand, proclaim, and live the saving Gospel (2Ti 3:16–17; see Q018, Q056).
