The Lord used one paragraph of text to convert me. He used a lot of other things, too—-my conversion was a long and messy process, and the Lord really put me through the wringer over a period of years. But it all hinged on a key moment when I read one paragraph that changed my life.

I was a deist for most of my youth and early adulthood. I had fallen in love with philosophy at an early age; I was consumed by a burning desire to figure out what was true about the universe and build a life that matched the cosmic truth. I went through a brief period of shallow engagement with Christianity, then turned away from it under the influence of critics like Rousseau and Emerson.

Emerson’s critique of the idea of human sinfulness was especially influential on me. He wrote that his thoughts and desires didn’t seem to him to be evil, and who else’s judgment could he ever trust, if he could not trust his own? He added that even if he knew his heart was evil, he would still have to follow it. What alternative is there for any creature, but to live as the kind of being it is? “Trust thyself,” he wrote. “Every heart vibrates to that iron string.”

I came back into contact with Christianity in graduate school. I had decided to write my dissertation on the reconciliation of religion and politics in the context of religious freedom. How do we maintain a moral order in society if we don’t share a religion?

That required me to read some Christian writing, including some apologetics. I started to see how some of the criticisms of Christianity were off base. And I was forced into contact with the historical evidence for Christianity. It became unavoidably clear to me that something pretty important had happened back there in Palestine.

I also learned the basic content of Christian theology in a way I had never known before, even during my earlier, superficial “Christian” period. I especially remember one conversation in the office of Nicholas Wolterstorff, who was advising my dissertation. He somehow forced into my head a real understanding of what the doctrine of the Incarnation actually claimed about the person of Jesus Christ. I sat there silent for a moment, then stammered out something like: “Oh. Oh, wow.”

But none of that pulverized my heart. Here’s what did.

One of the Christian books I had to read for my dissertation was John Locke’s The Reasonableness of Christianity as Delivered in the Scriptures. Locke wrote that book in large part to persuade deists that Christianity is true, and that it does not require adopting any irrational beliefs. So in a way, I was the target audience.

I should note that in some important respects, Locke’s Reasonableness is not good theology. On some issues, Locke adopts dangerous theological compromises in a desire to reach his audience. Locke was not a deist, but he did bend too far to try to reach deists with the gospel. I would not recommend this book except for purposes of historical study.

However, in some ways there is also very good theology in the Reasonableness. One of the best sections is his defense of the holiness of God against the sinfulness of humanity. The Reasonableness was designed to cure people of deism, and however imperfect the medicine might have been, in my particular case the treatment did work.

Locke takes up the question, Why does God require perfect holiness before people can enter heaven? “It seems [to be] the unalterable purpose of the divine justice that no unrighteous person, no one that is guilty of any breach of the law, should be in paradise.”

That sentence made me sit bolt upright. This was the main obstacle between me and God. I had conceded ground to Christianity on one issue after another. The one thing I had never given an inch on was the principle of self-trust. I had allowed myself to forget about this key issue as my resistance to Christianity had been softening. Now I was hit smack in the face with it.

Citing Romans 3 and Galatians 3:21-22, Locke notes that no one has ever lived up to God’s standard of perfect holiness in all of history. If so, why did God set a standard so high no one has ever reached it? How is that fair or loving?

Here’s the paragraph that pulverized me:

Answer: It was such a law as the purity of God’s nature required, and must be the law of such a creature as man; unless God would have made him a rational creature, and not required him to have lived by the law of reason; but would have countenanced in him irregularity and disobedience to that light which he had and that rule which was suitable to his nature; which would have been to have authorized disorder, confusion, and wickedness in his creatures. For that this law was the law of reason—-or as it is called, of nature—-we shall see by and by. And if rational creatures will not live up to the rule of their reason, who shall excuse them? If you will admit them to forsake reason in one point, why not in another? Where will you stop? To disobey God in any part of his commands—-and ‘tis he that commands what reason does—-is direct rebellion; which, if dispensed with in any point, government and order are at an end, and there can be no bounds set to the lawless exorbitancy of unconfined man. The law therefore was, as St. Paul tells us (Romans 7:12) “holy, just, and good,” and such as it ought, and could not otherwise be.

My world was in ruins. The foundation of self-trust upon which I had built my life wasn’t just cracked; it was demolished to dust. And there was nothing underneath it. I was plummeting.

As a philosopher and especially as a deist, it was axiomatic for me that God is perfectly rational. Therefore the moral law is also the law of reason. And it’s the essence of philosophy that reason is an all or nothing proposition; to be a philosopher is to accept that there can be no legitimate deviation from reason on any point. Once you put these premises together, the conclusion is as plain as daylight: God must demand perfect holiness or cease to be God.

I stayed up nights working on this. There had to be a flaw in the logic!

There wasn’t. I gave up. As a good philosopher, I followed reason where it led me. I was a sinner, and God was absolutely right to demand perfect holiness from me or exclude me from his favor forever. I needed a savior.

As an undergraduate, I had attended the University of Virginia, founded by Thomas Jefferson, the grand old dean of American deism. He expressed the intellectual climate he wanted for his university in this way: “Here we are not afraid to follow truth wherever it may lead, nor to tolerate any error so long as reason is left free to combat it.”

I still wear the U.Va. T-shirt with that quote on it. But it means something different to me now.