Prolegomena / The Nature of Theology
The grounds and method of theological knowledge: why theology is necessary, how it differs from philosophy, and what role Scripture plays as the principium cognoscendi (the cognitive principle) of all doctrinal inquiry. The Shorter Catechism opens with the chief end of man; the Larger Catechism with the duty Scripture reveals.
Westminster Confession
1 section
Although the light of nature, and the works of creation and providence, do so far manifest the goodness, wisdom, and power of God, as to leave men inexcusable; yet are they not sufficient to give that knowledge of God, and of his will, which is necessary unto salvation; therefore it pleased the Lord, at sundry times, and in divers manners, to reveal himself, and to declare that his will unto his Church; and afterwards, for the better preserving and propagating of the truth, and for the more sure establishment and comfort of the Church against the corruption of the flesh, and the malice of Satan and of the world, to commit the same wholly unto writing; which maketh the holy Scripture to be most necessary; those former ways of God's revealing his will unto his people being now ceased.
Shorter Catechism
3 questions
Man's chief end is to glorify God, and to enjoy him for ever.
The Word of God, which is contained in the Scriptures of the Old and New Testaments, is the only rule to direct us how we may glorify and enjoy him.
The Scriptures principally teach what man is to believe concerning God, and what duty God requires of man.
Larger Catechism
4 questions
Man's chief and highest end is to glorify God, and fully to enjoy him forever.
The very light of nature in man, and the works of God, declare plainly that there is a God; but his word and Spirit only do sufficiently and effectually reveal him unto men for their salvation.
The holy scriptures of the Old and New Testaments are the word of God, the only rule of faith and obedience.
The scriptures principally teach, what man is to believe concerning God, and what duty God requires of man.