B.B. Warfield, a selection from "Calvin and Calvinism":
"Drawn out a little more into detail, this teaching is as follows. The knowledge of God is given in the very same act by which we know self. For when we know self, we must know it as it is: and that means we must know it as dependent, deprived, imperfect, and responsible being. To know self implies, therefore, the co-knowledge with self of that on which it is dependent, from which it derives, by the standard of which its imperfection is revealed, to which it is responsible. Of course, such a knowledge of self postulates a knowledge of God, in contrast with whom alone do we ever truly know self: but this only the more emphasises the fact that we know God in knowing self, and the relative priority of our knowledge of two objects of knowledge which we are conscious only of knowing together may for the moment be left undetermined. Meanwhile, it is clear than man has an instinctive and ineradicable knowledge of God, which, moreover, must produce appropriate reactions in his thought, feeling, and will, whence arises what we call religion. But these reactions are conditioned by the state of the soul which reacts. Although, then, man cannot avoid possessing a knowledge of God, and this innate knowledge of God is quickened and developed by the richest manifestations of God in nature and providence, which no man can escape either perceiving or so far apprehending, yet the actual knowledge of God which is framed in the human soul is affected by the subjective condition of the soul. The soul, being corrupted by sin, is dulled in its instinctive apprehension of God; and God's manifestations in nature and history is deflected in it. Accordingly the testimony of nature to God is insufficient that sinful man should know Him aright, and God has therefore supernaturally revealed Himself to His people and deposited this revelation of Himself in written scriptures. . . .
Calvin's ideas of the origin and nature of religion are set forth, if succinctly, yet with eminent clearness, in his second chapter. Wherever any knowledge of God exists, he tells us, there religion exists. He is not speaking here of a competent knowledge of God such as redeemed sinners have in Christ. But much less is he speaking of that mere notion that there is such a being as God which is sometimes called a knowledge of God. It may be possible to speculate on 'the essence' of God without being moved by it. But certainly it is impossible to form any vital conception of God without some movement of the intellect, feeling and will towards Him; and any real knowledge of God is inseparable from movements of piety towards Him. . . .
The natural revelation of God failing thus to produce its legitimate effects of a sound knowledge of God, because of the corruption of men's hearts, we are thrown back for any adequate knowledge of God upon supernatural activities of God communicating His truth to men . . . It is noticeable that Calvin does not pretend that this supernatural provision of knowledge of God to meet men's sin-born ignorance is as universal in its reach as the natural revelation which it supplements and, so far as efficiency is concerned, supersedes. On the contrary, he draws it expressly into a narrower circle. That general revelation 'presented itself to all eyes' and 'is more than sufficient to deprive the ingratitude of men of every excuse, since,' in it, 'God, in order to involve all mankind in the same guilt, sets an exhibition of His majesty, delineated in the creatures, before them all without exception."
I've shared these selections for two reasons. One is that some might see here what is today called "Reformed Epistemology." The other is that I'd like to suggest Warfield provides a key to go in another direction. I am not claiming that Warfield was clear about this other direction, but I am claiming that it is not clear he can be co-opted by Reformed Epistemology.
Reformed Epistemology says that all persons know God through the sensus divinitatis, an intuition of God that is innate and not inferred. However, in sin, humans suppress this and do not acknowledge God. Scripture is necessary for sinners to come to know God correctly.
By way of contrast, I'd like to suggest that the passages above say that the knowledge of God is inferred from the finite and temporal nature of man. We recognize that we are temporal, and that something must be eternal. However, rather than attributing eternality to God, humans attribute it to the material world, or finite deities, or the universe itself, or their own soul. Therefore, while it is clear by inference that God exists, humans suppress this clarity by holding to false beliefs about what is eternal.
On this second view, the religions of the world are attempts to claim that something is eternal which is not eternal. They reject the clear general revelation that is given in creation and providence. This explains the original sin of believing that humans can be like God, and it explains all ongoing sins of failing to know God. It leaves humans without excuse for their beliefs about what is eternal.
Scripture is necessary as redemptive revelation, to explain how God responds to the human failure to know what is clear from creation and providence. Special revelation is not universal, but is given in relation to humans being called out of unbelief.
I do not believe Warfield explicitly articulated this second line of thought, but I don't think he was explicitly a forerunner to Reformed Epistemology either. My claim is that this point has been ambiguous, and in a harmful way Reformed Epistemology continues this ambiguity. Natural theology is necessary to show, by inference and argument, that eternality cannot be attributed to anything but God the creator.