Shortly after I met my wife, Cindy, in 1989—she was living in New York City at the time, while I was living in Northern Virginia—she told me about a new church she was attending in Manhattan: Redeemer Presbyterian. The young minister, she told me, was “the best pastor in America.”

His name was Timothy J. Keller.

Since that time Keller, 69, has become one of the most consequential figures in American Christianity. When he founded Redeemer in the fall of 1989, fewer than 100 people attended; in the aftermath of the attacks on September 11, 2001, Keller was preaching in multiple services in three different venues each Sunday to about 5,000 people—mostly young, single, professionally and ethnically diverse. He has written about two dozen books, several of them best sellers. And unlike that of many popular ministers, his reach extends far beyond the Christian subculture.

In 2017, Keller retired as senior pastor of Redeemer, but he hasn’t slowed down. He’s chairman of Redeemer City to City, which has helped start more than 500 churches in many of the most influential cities in the world; he’s a visiting lecturer in pastoral theology at Reformed Theological Seminary New York City; and he’s one of the most in-demand evangelical speakers in the Christian world.

I met Keller through Cindy, and over the decades we’ve developed a close friendship, including conversations, in person and via email, about family and mutual friends, theology and philosophy, faith and science, and politics and books—and in just about every instance, I’ve come away at least a little more enlightened than I was, including on matters on which we might not fully agree. So it seemed like a good time to interview Keller, first in an hour-and-a-half phone conversation and then over email, to ask him to reflect on his past, Christian theology, and the role of Christianity in contemporary American society.

No two journeys of faith are alike, so I asked Keller about his. He was raised in the Lutheran Church in southeastern Pennsylvania. At Bucknell University in the late ’60s and early ’70s, he struggled with finding his identity, feeling that some of his desires were clashing with his conscience. “It was very confusing,” he told me. “I did struggle with who I was.” And then, he said, he came into contact with thoughtful Christians, “and they surprised me.”

For Keller, two things were going on at once. On the one hand, he started seriously engaging with Christians and Christianity by reading books about faith, including some by C. S. Lewis and the biblical scholar F. F. Bruce. (Some of the things that most stand out about Keller are his scholarly cast of mind, intellectual curiosity, and recall.)

“I took a rational path, I would say, toward being a Christian,” Keller told me. “I’m the kind of person, I don’t trust my feelings. And if I was going to embrace Christianity fully, I wanted to really believe it was intellectually credible.” He led with the intellectual, he said, “because I was afraid that I was going to come up with some faith that just met my emotional needs and that wasn’t real. And would crumble. I was afraid it would crumble later on in life as I started getting older and reading more books. I didn’t want something that was going to crumble as I got older.”

On the other hand, according to Keller, “I really did need something to help me sift my inner feelings to figure out who I was, and which of these inner feelings is me and which of these is not.”

That “something” turned out to be the Christian faith, to which he converted at the end of his sophomore year. For Keller, faith involved the convergence of mind and heart. “I tend to think a fully formed Christian is somebody who finds Christianity both rationally and intellectually credible, but also emotionally and existentially true and satisfying,” he said.

After his conversion, Keller almost immediately decided he wanted to be a minister. So after graduating from Bucknell, he enrolled at Gordon-Conwell Theological Seminary, where he met his future wife, Kathy. (Kathy earned a master’s in theological studies at Gordon-Conwell; it’s nearly impossible to overstate her significance to almost every important area in Keller’s life.) At the age of 24, Keller became the sole minister of West Hopewell Presbyterian Church, in rural Virginia, where he pastored for nine years. By the time he was 33, he had delivered about 1,500 sermons—three a week, each on a different topic.

Not many people know about this part of Keller’s life, and I was intrigued by the juxtaposition: Keller, who has been called “a pioneer of the new urban Christians” for his work in Manhattan, spent nearly a decade pastoring a church in a community where only 5 percent of the local high-school graduates went on to college.

“They were utterly different places to preach and to pastor,” Keller said. The illustrations, metaphors, and cited sources he used were quite different. Quoting Friedrich Nietzsche, for example, can work in New York City in a way it wouldn’t in Hopewell. In one place, you’re likely to deal with investment bankers and masters of the universe; in the other, you’re interacting with factory workers and people who grew up in an agrarian economy.

Additionally, Keller said, in a rural church like Hopewell, “you’re in everybody’s lives. You go to their Sweet 16 parties, you go to their graduations, you watch them die, you hold their hands as they’re dying, you walk through divorces, you’re there for absolutely everything.” It’s a very different situation in a big city, he told me, where people in the congregation come to see you for counseling during office hours.

But what I found most interesting is that, as Keller explained it, “in a blue-collar town, your pastoral work sets up your preaching.” Unless congregants have gotten to know you personally, unless you’ve supported them through all kinds of problems and shown wisdom in the way you as a minister treat them, they won’t listen to your preaching. They have to trust you first.

In a place like New York, however, “people look for expertise; they’re professionals, and they want to know you’ve got the goods; they want to know you’re really good at what you do. And if they hear you and they say, ‘Oh, that’s smart, that’s very interesting, that’s very skillful,’ then they’ll come and talk to you about their problems.”

Turning to theology, I probed Keller on the challenge to faith posed by theodicy. Channeling David Hume in Dialogues Concerning Natural Religion, how does Keller explain why an all-good, all-loving, and all-powerful God allows for the existence of evil and suffering in the world? It’s a question to which I have long thought Christian philosophers (and nonphilosophers) offer at best an incomplete response. (I’ve made my own inadequate efforts to wrestle with this issue as a Christian.)

Keller, who was an associate practical-theology professor at Westminster Theological Seminary before founding Redeemer Presbyterian, answered in two parts. On the pastoral side, he said that the wrong answer, especially for a person who has experienced suffering or grief, is: “Don’t question; God has his reasons.”

The whole Book of Job is a testimony to the Bible’s invitation to us to struggle and cry out in suffering, Keller told me. “After Job does this for 40 chapters, God vindicates him,” he said. “This is no call to stoicism or ‘Don’t question.’” Job is “a book showing [that] God is patient with us in suffering and always present even when he seems absent.” So when dealing with someone who is suffering, “you start with Christ’s suffering, his walking with us in the furnace, his giving us his love and presence, though not all the answers.”

But if you are talking with someone who is not suffering but wants to disprove God on this basis, Keller offered a more direct answer. Citing the philosopher Alvin Plantinga, Keller said that if you believe in God, evil and suffering are a great problem, “but if you don’t believe in God, it’s a bigger one.” To believe in evil requires a belief in moral absolutes grounded in some transcendent truth. If that doesn’t exist, then how do you even define evil?

“If there is no God, then evil and suffering and violence are perfectly natural,” Keller told me. “The weak are killed off; the stronger survive. That’s the way the world is. There is no right and wrong—there is just what is. To believe that some things that happen are evil requires some supernatural standard of good—something from outside of nature—by which to judge which natural things are truly natural and which things are unnatural. But as Nietzsche says, there is nothing outside of nature.”

This theological argument doesn’t explain why God allows evil and suffering; it only claims that you can’t use evil and suffering to disprove the existence of God. “That’s all they can do,” Keller said. “That’s it, and that’s not much. It’s the cross that helps us actually live this life. That’s what matters.”

Staying with this line of inquiry, I asked Keller to sketch the limitations of or problems with the secular view of scientism (the belief that science is the only source of real knowledge) and materialism (that physical matter is the fundamental reality).

Keller told me that recent books such as Science and the Good, by James Davison Hunter and Paul Nedelisky, and Atheist Overreach, by Christian Smith, do a good job of making the case that has also been made by the German philosopher Jürgen Habermas.

In a nutshell, their point is that science can tell you what you can do and how to do it efficiently, but it can never tell you whether you ought to do it. Science can’t get you from the “is” to the “ought”; it can’t give us a basis for morality. And if science and objective human reasoning can’t give us that, Keller told me, “we will not be able to order our society without recourse to religion or faith of some kind.”

“Right now, a big part of the polarization we are seeing is due to ‘warring moralities’ that come from differing assumptions about the big questions,” Keller said. “What are human beings for? How do we make moral judgments? What are the highest goods? Science can’t adjudicate these controversies.”

Beyond that, Keller said, the philosophy of secular materialism—the view that there is no transcendent, supernatural dimension; no God; no soul—can’t really support its own moral values.

“This is a major theme of the philosopher Charles Taylor,” Keller told me. “In short, he says that secular materialism has to explain our moral beliefs as merely the result of evolution and biology, or of social construction, or both. There are no moral absolutes grounded in a cosmic order, as the Greeks thought, or in God and heaven.

“Materialism logically leads to at least soft relativism,” he added. “And yet modern secular people are highly moral—committed to the values of human rights and justice for the poor and marginalized. So, Taylor and others conclude, the conundrum of modern society is that we don’t have the moral sources to support our high moral ideals. We teach people in college that all facts and moral claims are socially constructed, and then we demand they give up their power and privilege to lift up the marginalized. But why, then? As C. S. Lewis said about this very dynamic [in The Abolition of Man], ‘We castrate and bid the geldings be fruitful.’”

On the matter of faith, I mentioned to Keller that just the day before our interview, I had dinner with a few close friends, one of whom is an atheist. We discussed faith, and he told me he tried to believe in God when he was young, but that he’s not hardwired to believe. The way he described it is, it’s like asking a person who was born color-blind to see color. Faith is “on another frequency.” What does Keller say to those who think faith is a gift: They don’t have it, and you can’t will it?

Keller’s response is that to say faith is a gift is not the same thing as saying we should be passive. Reason and inquiry have a role to play, even if faith by its very nature isn’t something people can arrive at through a series of logical proofs. (“Faith is the substance of things hoped for, the evidence of things not seen,” according to the Book of Hebrews.) But Keller added this observation: Why don’t these people take a look at all the faith they’re exercising already?

“Most people say, ‘I just don’t have the faith,’” he said. “And I say, ‘You’re already basing your life on all sorts of things you can’t prove.’ Say, for example, everybody who believes in human rights. Anybody who has any moral intuition about human rights at all—just because we live in a liberal society, it seems like a given, but the reality is, of course, there’s no way to prove that. Science can’t prove that all people are equal. That’s an act of faith. And in fact, even when people rely on their own intuitions and distrust authority, that’s also an act of faith.”

In other words, we are all going through life making assumptions and “leaps of faith” (to use a phrase from the 19th-century Danish philosopher Søren Kierkegaard); we just don’t recognize them as such. Certain assumptions are ingrained in us, imbibed through our culture, so we take them to be true even though they are acts of faith. Opposing slavery and racism, anti-Semitism, eugenics, infanticide, misogyny, and other forms of injustice requires a belief in inherent human dignity. But that is not a proposition we can prove; it is a proposition we choose to believe.

“Just recognize that everything you hold dear right now is a mixture of reason and faith,” Keller told me. “You can rationally sift a lot of these various positions, but you can’t ultimately prove them. Don’t look at Christianity as radically different than believing in human rights or believing in your particular understanding of racial justice and that sort of thing.”

Turning to Christianity in the context of contemporary American politics, I asked Keller about the relationship of the Church, and in particular evangelicalism, to politics. The upshot of Keller’s position is that whereas individual Christians should be engaged in the political realm, the Bible makes it impossible as a Church to hitch your wagon to one political party, especially in these times. “For Christians just to completely hook up with one party or another is really idolatry,” Keller said. “It’s also reducing the Gospel to a political agenda.” (He pointed me to an address by Nathan Hatch, president of Wake Forest University, called “The Political Captivity of the Faithful,” with which he concurs.)

Keller noted that this danger isn’t new. As is his wont, he cited a book to help me more fully understand his argument—H. Richard Niebuhr’s The Social Sources of Denominationalism, which holds that denominationalism is primarily a social phenomenon that tends to be captured by different political and social classes. Keller observed that because Christianity properly understood is not a legalistic religion—“there is no New Testament Book of Leviticus,” he told me—it can be a part of almost any culture. In that sense, it’s a fairly flexible faith. “Christians are always more incarnate in the culture—and the danger of that is that they get captured by it. That’s always been a problem,” he said. There’s ever the danger of “cultural and political captivity.”

When I pressed the point further, Keller admitted he believes that “most Christians are just nowhere nearly as deeply immersed in the scripture and in theology as they are in their respective social-media bubbles and News Feed bubbles. To be honest, I think the ‘woke’ evangelicals are just much more influenced by MSNBC and liberal Twitter. The conservative Christians are much more influenced by Fox News and their particular loops. And they’re [both] living in those things eight to 10 hours a day. They go to church once a week, and they’re just not immersed in the kind of biblical theological study that would nuance that stuff.” Too often, he believes, there’s no relationship between a proper Christian ethic and the way it translates into political and cultural engagement. It’s not the doctrine that’s at fault, Keller would argue; it’s the way people are taught and interpret it. It’s a failure of imagination and hermeneutics.

The way I have put it is that faith is often subordinated to partisan politics and political ideology, with the latter being the prism through which too many Christians interpret the former. Too many Christians are characterized by their tribal commitments, rather than an understanding of justice and human teleology.

On Donald Trump, Keller said that unlike a generation ago, many evangelicals are not looking to put Christians into power in order to turn the culture back to God; now they are looking for a protector, a champion.

“Both those evangelical strategies are wrong,” Keller told me. “Both of them are about power and saying, How are we going to use power to live life the way we want? They’re not enough about service; they’re not enough about serving the common good.

“The proper cultural strategy is faithful presence within,” he added, “not pulling away from the culture, and not trying to take it over. ‘Faithful presence within’ means being faithful; it means we’re not going to assimilate, [but] we’re going to be distinctively Christian. It’s about an attitude of service, uncompromising in our beliefs, but not withdrawing and not trying to dominate.”

It takes real (and rare) wisdom to navigate between the Scylla and Charybdis of dominance and withdrawal, between control of the culture through political power, which is hardly a biblical archetype, and complete cultural separatism.

My final question to Keller during our phone interview was his take on the spiritual temperature of the nation. What sorts of yearnings does he see and sense, and how can Christianity, properly understood, speak to those yearnings?

“I think the perplexity I see is that people want to have a foundation for making moral statements, but at the same time, they want to be free, and so they want to talk about the fact that all moral statements are culturally constructed,” he told me. “And so when somebody pushes a little bit on their life, they’d say, ‘All truth and all fact, all facts and all moral statements, are culturally constructed.’”

As Keller pointed out, they’re creating, at least philosophically, a kind of relativism, though of course no one actually lives like a relativist. All except sociopaths believe in certain deep truths about right and wrong, human nature, justice and a good life. “What we need is a non-oppressive moral absolute,” in Keller’s words. “We need moral absolutes that don’t turn the bearers of those moral absolutes into oppressors themselves.”

Keller concluded our conversation with a sentence that summarizes his consequential life: “I actually think the Christian faith has got all the resources you need.”

Peter Wehner is a contributing writer at The Atlantic, a senior fellow at the Ethics and Public Policy Center, and Egan visiting professor at Duke University. He writes widely on political, cultural, religious, and national-security issues, and he is the author of The Death of Politics: How to Heal Our Frayed Republic After Trump.