At its heart, this is the dilemma of all human knowledge. We reach out to grasp a world we know to be more complex than our capacity to understand it, and we choose and act despite our awareness that what we take to be true may be an illusion, a wispy misperception. Plato captured this uncertainty in a famous allegory. Humans live, he suggested, as if chained within a cave with their backs to the entrance, able to see no more than the wall before them, forced to infer the nature of the real objects in the world from the flickering shadows those objects cast as they pass before a fire at the entrance of the cave.

Divinity poses a special sort of problem in epistemology. You cannot kick a stone and refute the argument from skepticism, as Samuel John- son did when confronted with Bishop Berkeley's doubts that the world existed. There is no stone to kick. It is the essential nature of divinity that divinity is nonmaterial. There is nothing physical that a Christian can pick up and show to a non-Christian as irrevocable material proof of the existence of the Christian God; nor is there irrevocable physical evidence against that God's reality. Even if a believer is prepared to accept the existence of divinity without question, the knowledge that our humanness limits our understanding of God's real nature means that each believer is constantly making judgments about whom to trust about the specifics.

This is the problem of presence: that the evidence for divinity does not come directly from the senses. It usually comes indirectly, from other, more unreliable, sources.

Those who say they know God are legion, and their testimony includes the earliest written texts to have survived the harshness of the Egyptian desert and last week's telephone call from your great-aunt Mildred. Any one person who has faith must believe that at least some of those who claim to know God are simply wrong. Few people who have faith are, I believe, willing to say that all those mistakes are malicious or mad. Most people, whatever their religious persuasion, assume that there are decent human beings with good intentions who have interpreted the evidence differently and are wrong. Most people who attend church disagree with some people in their churches at some times, sometimes even with their pastors or their friends, over the interpretation of a biblical text, over the decision about what kind of spiritual education their children need, over their conviction that a particular political judgment follows from a particular understanding of God. Those who have faith are acutely aware that all humans look out at the world from behind lenses that distort what is there to be seen.

So how, in the face of doubt and uncertainty, does God become real for someone? Particularly in our modern—or postmodern or late modern—American society, with all its exposure to scientific explanation, where the supernatural is often treated as entertaining fantasy, how does some- one become confident that there is a supernatural God present in the everyday world? How does a living God become real to modern people?

I am an anthropologist, and in all likelihood I chose my profession because I have lived these questions. I have three cousins, sons of my mother's sisters. Each of them is a deeply conservative Christian, of the sort my secular friends would call fundamentalist. My mother's father was a Baptist minister, but my mother rebelled. My father's father was a Christian Scientist, but my father, too, rebelled—he became a doctor— and when I was a child, we went to a Unitarian church. Neither of them was willing to give up on church, but for neither of them did God really exist as a being in the world. When we met for larger family holidays, the conversations flowed around and past one another as my grandparents prayed, and my parents bowed their heads politely, and my cousins played in a world I did not understand. When I entered grade school, our family moved to a suburban town in New Jersey. The little girl in the house behind our garden was an Orthodox Jew, and on Friday evenings I would go over for dinner and turn the electricity on and off for them, a task that their religion forbade them to do. There is a name for such a helpful Gentile in Jewish households—a shabbas goy—but the apparent fiddle with the rules made my mother uneasy.