Let us review the insufficiency of human reason to obtain from the mere light of nature a competent knowledge of God, and of his will concerning us. The light of nature furnishes us with little or no knowledge of the moral character and government of God. While man was in a state of innocence, indeed, he might, by reflecting on his own mind, understand something of the character of that Divine original after whose image he was created; but, having sinned, this image is effaced. It is also true that the judgments of God against sinners are manifest in all the earth; and every man’s conscience bears witness that what is wrong in another towards him must be wrong in him towards another; and that, having felt and acted contrary to this equitable principle, in innumerable instances, he is a sinner; but as to the evil nature of sin as committed against God, and his own lost condition, conscience itself can yield him little or no information. And as to an hereafter, whether there be any, and, if there be, what it will prove; whether we shall have to give account of the deeds done in the body; whether there will be any hope of forgiveness; and what we must do to be saved—all is darkness The light of nature, though sufficient to bear witness for God, and so to leave sinners without excuse, was never designed in any state to furnish man with all he needed. Even in innocence man was governed by a revealed law. It does not appear that he was left to find out the character or will of his Creator by his reason, though reason, being under the influence of rectitude, would lead him, as he understood the mind of God, to love and obey it. But if revelation was necessary in innocence, much more now man’s foolish heart is darkened by sin.

The state of the heathen, who are without Divine revelation, furnishes awful proof of its necessity. The grossness of their thoughts of God, and of an hereafter, is such, that those who have received the light of revelation can scarcely think it possible for rational beings to entertain them. To say nothing of the uncivilized heathen, even the polished sons of Greece and Rome, thou prodigies in science, yet, in relation to these things, were the subjects of the most sottish stupidity. Well is it said, “The world by wisdom knew not God.” That small portion of real light which on these subjects appears in the writings of our modern deists, is borrowed from those very writings which they mean to depreciate. They live in the neighbourhood of revelation, and, whether they will own it or not, are enlightened by it. The speculations of those who have had only the light of nature to guide them are, in respect of God and religion, absurd in the extreme.

Man is said to be wiser than the beasts of the field; but is principally by means of instruction. We are born, it is true, with an immortal mind; but, uninformed, what is it? Knowledge chiefly enters in at the door of the senses. To what do we owe the gift of speech? It seems to be natural to us; but if we look at one who is born deaf, we shall find him dumb also; and if to this be added blindness, there will be but little difference between him and the beasts of the field. But if we need human instruction for the attainment of knowledge in things of this life, is it surprising that we should need a Divine instructor for things heavenly and Divine? It is true that God instructs us, as has been said, by his works; but they contain only a few of the rudiments of Divine knowledge; like the parables of our Saviour, they were not designed to furnish perfect information on the subject, but merely a general intimation, tending to excite humble inquiry for further instruction; which, when asked, was readily granted, but, when set at nought, it was “seeing and not perceiving, hearing and not understanding; lest they should be converted and healed.” The apostle, in his address to the Athenians, represents it as the design of God, in his works of creation and providence, to lead men to seek him; but though he was not far from every one, seeing all live, and move, and have their being in him, yet the light of nature could only enable them “to feel after him, if haply they might find him.” Though “the heavens declare the glory of God, and the firmament showeth his handiwork;” though “day unto day uttereth speech, and night unto night showeth knowledge,” and though their voice is heard in every language and in every clime, even to the end of the world; yet it is not by them, but by the word of Jehovah, that souls are converted, and the simple made wise. Some of the wisest among the old heathens felt and acknowledged the need there was of a revelation from heaven; and heathens of the present day acknowledge the same thing. A Hindoo fakeer, who was a brahmin goroo, being lately asked by one of his disciples, who had heard a missionary at Balasore, whether he could make known to him the living and only God, answered, “We know there is one living God, besides Kreshnoo, Seeb, and Ram; but we do not know his way.” The disciple replied, “Come to the Sahib Fakeer; he will tell you of the God of heaven, whose way he knows.”

Fuller, A. G. (1988). “The Necessity of Divine Revelation,” Letters on Systematic Divinity. The Complete Works of Andrew Fuller: Memoirs, Sermons, Etc. (J. Belcher, Ed.; Vol. 1, pp. 696–697). Sprinkle Publications.