The Westminster Confession (Chapter I.2–3) lists the sixty-six books of the Protestant canon as 'the Word of God written' and explicitly states that 'the books commonly called Apocrypha, not being of divine inspiration, are no part of the canon of the Scripture; and therefore are of no authority in the church of God, nor to be any otherwise approved, or made use of, than other human writings.' This is one of the clearest confessional rejections of the Deuterocanon in any Protestant standard.

The authority of Scripture rests not on the testimony of any man or church but 'wholly upon God (who is truth itself) the author thereof.' The Westminster Confession articulates the principle of Scripture's self-authentication (autopistia) — the Holy Spirit witnesses in and by the Word that it is the Word of God — alongside external arguments from antiquity, consent, doctrinal excellence, and miracles. This dual basis for scriptural authority is characteristic of Westminster epistemology.