The English Puritan Stephen Charnock (1628–1680), in his famous work The Existence and Attributes of God, said the following about God’s existence and the proper objects of reason and faith:
Men that will not listen to Scripture, as having no counterpart of it in their souls, cannot easily deny natural reason, which riseth up on all sides for the justification of this truth [the folly of atheism]. There is a natural as well as a revealed knowledge, and the book of the creatures is legible in declaring the being of a God, as well as the Scriptures are in declaring the nature of a God; there are outward objects in the world, and common principles in the conscience, whence it may be inferred.
For God in regard of his existence is not only the discovery of faith, but of reason. God hath revealed not only his being, but some sparks of his eternal power and godhead in his works, as well as in his word. (Rom. 1:19, 20), “God hath showed it unto them,”—how in his works; by the things that are made, it is a discovery to our reason, as shining in the creatures; and an object of our faith as breaking out upon us in the Scriptures: it is an article of our faith, and an article of our reason. Faith supposeth natural knowledge, as grace supposeth nature. Faith indeed is properly of things above reason, purely depending upon revelation. What can be demonstrated by natural light, is not so properly the object of faith; though in regard of the addition of a certainty by revelation it is so.
The principal objects of faith are those truths above reason (e.g., the Trinity), not the truths discoverable by reason, though faith provides certainty on matters of reason, such as the existence of God. Faith therefore is supplemental for truths discoverable through reason and not the necessary epistemic ground for knowledge of such truths.