I’m convinced that many things foundational to a Christian worldview are things people already believe without having to be persuaded. Most believe, for example, the universe has been designed by a person (Genesis 1:1). They may not admit it outright, but constant references to “Mother Nature” betray their deeper convictions. They believe humans are special, valuable in a transcendent way (Genesis 1:27). That’s why it’s OK to gas termites, but not people. They are also convinced that although man is valuable, something is wrong. In general, people court vice as much as virtue (Romans 3:23). This surfaces as the problem of evil.

Each of these essential elements of a Christian worldview is something everyone knows. But how? Intuition.

When I say intuition, I mean something very particular. I don’t mean a hunch. I don’t mean a line of reasoning to a conclusion or a skill learned over time–like the way a seasoned batter “senses” where the next pitch will come.

In fact, intuitions are not learned at all. They are something we’re born with, information built into our minds by a wise Creator. The founding fathers of the United States called them “self-evident” truths.

During a recent Q & A session after I lectured at a liberal college, I asked a student if he knew what he was thinking just then. Of course he did. But how did he know? Did he need a scientist’s report on the physical states of his brain to know his own thoughts? Of course not. He had immediate and direct access to his own mind. Such things we take for granted. Even to raise the question seems foolish.

Knowledge by intuition is like that. It is immediate, direct and obvious. And, because our intuitive awareness gives us reliable truth about our world, it can be a powerful ally in evangelism if we know how to use it.

During a “Science and Faith” conference some years ago, I was asked to prove there was purpose in the universe. I answered that purpose isn’t something we need to argue for; it’s something we already know intuitively.

For example, ask if a person would ever try to talk someone out of suicide. If so, why? I suspect he’d say suicide is a waste of a valuable life. But how can a life be wasted if it has no ultimate purpose? Has he ever bemoaned the tragic death of a promising high school student? Or a child taken by disease or natural disaster? Or Princess Diana who perished in the prime of life? All of these seem to be shocking and “untimely” deaths. Yet why would anyone expect a life without purpose to have an appointed end?

Our reactions to examples like these are spontaneous, immediate and intuitive. Deep down inside we know that each person’s life is meant for something, a goal that these catastrophes interrupted. But what is ultimately tragic about any death if life has no intrinsic purpose? Our response to these things demonstrates we actually agree with Scripture that people have purpose beyond their temporal existence (Ecclesiastes 3:11).

At this point there is an important question you must ask: What view of the world makes sense out of the idea that human beings have purpose? Or that the universe has a designer? Or that humans are valuable, but broken, in need of forgiveness and redemption?

Do you see what I’ve done? I start with a common experience, then ask questions to get people in touch with their own intuitive knowledge about it. Then I ask them to make sense out of it. As a Christian, I don’t have to wonder. The Bible explains it. The truths of Christianity resonate with our deepest intuitions about the way the world actually is.

I call this tactic “Back of the Book.” I know things about what other people know, even if they are not immediately aware of them. I know their secrets, in a sense, because God has revealed them. I’ve read the back of the book. I know the story’s end.

C.S. Lewis used this knowledge masterfully. The opening chapters of his classic, “Mere Christianity,” are devoted to unpacking our intuitive awareness of morality. Later, in “The Abolition of Man,” Lewis documents some of the content of this universal knowledge evident in every culture: proscriptions on murder, theft, rape, adultery; and praise for heroism, altruism, self-denial and honesty.

In his book “Unshakable Faith,” Alex McFarland observes the following:

“Lewis’s study (and others by Christian apologists and sociologists) proved that different people groups and cultures, though having no contact with each other, nevertheless had similar moral codes and ethical structures by which they lived. That’s not to say that humans always do what is morally right; Lewis and others assert that all cultures, intuitively know what is right [emphasis added].”

Let me give you a dramatic example of how I capitalize on this in a university setting. When I lectured on moral relativism to an audience at Berkeley, I told the students that I knew something about them that they knew about themselves, but didn’t know I knew: They each had a bad self image. How did I know that? Because everybody has a bad self image, myself included.

In our most honest moments, I said, we look down inside ourselves and see something twisted and ugly, a moral brokenness we cannot deny. In fact, we have a strong feeling associated with this problem, and that feeling has a name. “What is it?” I asked.

The audience gave me the same answer I always get in those situations: Guilt. Then I asked why they feel guilty. “Maybe it’s a social construction,” I offered, “or a power move by culture. That might be the answer. But there’s another possibility,” I said. “Maybe you feel guilty because you are guilty. Does that answer resonate with you?”

I have asked this question countless times on campus. No one has ever stopped me afterwards and said I was wrong, that guilt isn’t real for them. They could not. They knew better–which made my closing statement all the more powerful. “The answer to guilt is not denial,” I said. “The answer to guilt is forgiveness. And this is where Jesus comes in.”

You see, even in the totally secularized environment of a quintessentially liberal university, the foundational truths of Christianity have the ring of truth to them.

Because God’s Word tells us true things about every human being–awareness of God’s existence, the sense of our own value, a knowledge of our own sin and guilt–we can appeal to those things. Even if a person denies they are true, you know he’s lying to himself. In his heart of hearts he agrees with you, and in unguarded moments his own lips affirm it.

You don’t have to convince him of these things. He knows them already.