"Natural Religion": Can a Man Be Saved by God's Revelation in Man and Nature?

The Bible clearly teaches that God reveals Himself in His creation, such that unbelief is a suppression of knowledge, leaving the unbeliever without excuse, whether he has heard the Gospel or not (e. g., Psalm 19:1-4, Romans 1:18-22). That is half the equation. The other half is what I am addressing here: can a person be converted by what he can know of God from the creation, apart from ever hearing the word of God?

In general, theologians have answered this question with a "no." That is because the Bible also tells us that men are converted, under normal circumstances, only by the preaching of the Word of God: "How then will they call on Him in whom they have not believed? And how are they to believe in Him of whom they have never heard? And how are they to hear without someone preaching? And how are they to preach unless they are sent? As it is written, 'How beautiful are the feet of those who preach the good news!' But they have not all obeyed the gospel. For Isaiah says, 'Lord, who has believed what he has heard from us?' So faith comes from hearing, and hearing through the word of Christ" (Romans 10:14-17).

There are exceptions. For example, we can think of John the Baptist, who was regenerate in the womb (Luke 1:15). Or we might think of infants who die, or the mentally-disabled. Theologians have also been conscious of these exceptions. For example, we find this in the Westminster Confession of Faith: "Elect infants, dying in infancy, are regenerated and saved by Christ through the Spirit, who worketh when, and where, and how He pleaseth. So also are all other elect persons who are incapable of being outwardly called by the ministry of the Word" (X:3).

However, apart from those exceptions, I think that the Scriptures require us to consider the Holy Spirit's speaking through the Word to be the only means of conversion of fallen men. "In the present condition of our race, whatever may be the evidences which exist within us and around us of the being, perfection, and character of God, of the condition of man, and the relation he sustains to his Creator, his darkened faculties are incompetent to gather from them the conceptions which make up the fabric of natural religion, however he may prove its truth from those sources, after the ideas have been suggested to the mind" (James Henley Thornwell, "The Necessity and Nature of Christianity").