Q. What do the Scriptures principally teach?
A. The Scriptures principally teach, what man is to believe concerning God, and what duty God requires of man (2 Tim. 1:13)
Chapter I: Of the Holy Scripture
V. We may be moved and induced by the testimony of the Church to an high and reverent esteem of the Holy Scripture. And the heavenliness of the matter, the efficacy of the doctrine, the majesty of the style, the consent of all the parts, the scope of the whole (which is, to give all glory to God), the full discovery it makes of the only way of man’s salvation, the many other incomparable excellencies, and the entire perfection thereof, are arguments whereby it does abundantly evidence itself to be the Word of God: yet notwithstanding, our full persuasion and assurance of the infallible truth and divine authority thereof, is from the inward work of the Holy Spirit bearing witness by and with the Word in our hearts.
For more on this subject, please visit the Systematic Theology page.