The RCA affirms the Protestant biblical canon of 66 books: 39 Old Testament books and 27 New Testament books. This canon was not determined arbitrarily but was recognized by the church as containing the marks of apostolic authority and being universally received throughout the church.

The books of the Apocrypha (Deuterocanonical works) are recognized as historically valuable and useful for the church but are not considered part of the canon of Scripture. This reflects Reformed rejection of the additions made to the canon at the Council of Trent.

The RCA affirms the principle of sola scriptura: Scripture alone is the supreme authority for faith and practice. The canon is closed—no new writings are being added. This principle grounds the RCA's resistance to extrabiblical authorities and its commitment to biblical authority in all matters of doctrine and practice.