“Natural theology” — the belief that man inherently has the ability to reason himself to God — is surging in popularity among evangelicals. But does it find support in Scripture?

In Romans 1, Paul presents a strong case against the idea of natural theology. It is true that God reveals Himself in creation. He reveals Himself also in our consciences, through the moral law He has written on the human heart (Romans 2:15). But that knowledge is not enough to save. Romans 1:18 says, “For the wrath of God is revealed from heaven against all ungodliness and unrighteousness of men who suppress the truth in unrighteousness.” The sinner, in his natural condition, is dead in trespasses and sins (Ephesians 2:1), and dead means dead — he can’t respond. He is lost, ignorant, and utterly blind to the glorious light of the gospel.

So even if the sinner, through nothing but his own powers of deduction, concludes there is a powerful, law-giving God who has established the standard for morality, what can the sinner do with that truth? Does he innately have the capability to move from that to salvation? No, Paul tells us that the response of the unbelieving heart is to suppress the truth. He suppresses it in unrighteousness because he is, at his core, wicked, corrupt, sinful, and incapable of any true righteousness.

Paul continues,

Because that which is known about God is evident within them; for God made it evident to them. For since the creation of the world His invisible attributes, His eternal power and divine nature, have been clearly seen, being understood through what has been made. (Romans 1:19–20)

Why? So sinners can conjure their own salvation? No! Paul says, “So that they are without excuse” (Romans 1:20). God’s self-revelation through His creation is not enough to save sinners — it’s only enough to damn them.

And “even though they knew God, they did not honor Him as God or give thanks, but they became futile in their speculations, and their foolish heart was darkened” (Romans 1:21). Whatever faint glimmer of light a person might find on the path of reason and conscience quickly goes dark — actually, the sinner snuffs it out himself.

That truth is at the heart of the whole biblical understanding of salvation. This fact lies at the foundation of the gospel: The sinner is utterly unable and unwilling to believe the truth by himself. This might be the most important doctrine in all of Scripture, because if you get it wrong, you’re going to be wrong about everything that follows.

People frequently get hung up on the sovereignty of God in salvation. But you can’t hope to fathom God’s work in salvation without first understanding the sinfulness of humanity. Only then is it clear that the only way a sinner can ever be saved is if God radically redeems and transforms him, giving life to the dead.

Apart from that intervening divine act, sinners’ only instinct is to dishonor God. Spiritual darkness reigns in their hearts, and their thinking only becomes more futile and more bent against God. Paul says, “Professing to be wise, they became fools, and exchanged the glory of the incorruptible God for an image” (Romans 1:22–23).

God’s creation speaks to His character. He has planted testimony of Himself in the created world, and woven it into the fabric of humanity. But the only thing sinful man can do is reject it, pervert it, and ignore it. The evidence of God’s existence and nature may only amount to a faint, flickering flame in a world dominated by darkness, but sinners are all too eager to blow it out just the same. And for that reason, they stand justifiably condemned.

In the subsequent verses, Paul describes how the sinner’s rejection of God leads to his utter degradation and corruption. It’s a wicked and perverse descent — one we routinely see in the world around us. It’s really the story of human history, repeated over and over in a futile, repulsive cycle of depraved destruction. In The Intellectuals, author Paul Johnson shares a series of stories about individuals including Rousseau, Kant, and other great thinkers who helped shape Western culture. What strikes you is not just their brilliance, but how perverse and deviant their lives were. Their intelligence is undeniable, but it couldn’t save them from the disastrous degradation of Romans 1.

What does natural theology ultimately get us? Paul says it leads to

being filled with all unrighteousness, wickedness, greed, evil; full of envy, murder, strife, deceit, malice; they are gossips, slanderers, haters of God, insolent, arrogant, boastful, inventors of evil, disobedient to parents, without understanding, untrustworthy, unloving, unmerciful; and although they know the ordinance of God, that those who practice such things are worthy of death, they not only do the same, but also give hearty approval to those who practice them. (Romans 1:29-32)

Far from finding God on his own, the unrepentant man becomes a champion and a cheerleader for everything the Lord opposes.