Christian Churches affirm the Protestant canon of 66 books: 39 Old Testament books and 27 New Testament books. This canonical collection represents the complete revelation of God in Scripture and is the sole written authority for doctrine and practice. The Restoration principle 'no book but the Bible' affirms biblical authority and sufficiency.

The Old Testament is recognized as the Hebrew canon (excluding deuterocanonical books such as the Apocrypha). These 39 books correspond to the Hebrew scriptures that Jesus and the apostles recognized as authoritative (3 segments: Law, Prophets, Writings, totaling 24 or 39 books depending on counting method). The deuterocanonical books are honored as helpful historical documents but are not considered canonical Scripture.

The New Testament canon of 27 books represents the writings explicitly affirmed by the early church as apostolic and inspired, including the four gospels, Acts, Paul's epistles, Hebrews, James, 1-2 Peter, 1-3 John, Jude, and Revelation. The canon is closed: no additional books should be added, and no books within the canon should be removed based on personal preference or cultural accommodation.