Faith is hard because it is a decision to live as if a set of claims are real, even when one doubts: in the Christian case, that the world is good; that love endures; that you should live your life as if the promise of joy were at least a possibility. These are not intellectual judgments on the same order as deciding how many apples you should buy at the market. They are ways of experiencing life, attitudes we take toward living in the world. The Gospels clearly present the commitment to faith as a choice in the face of the uncertainty of human knowledge. Indeed, most Christians believe quite explicitly that what humans understand about God is obscured by the deep stuff of their humanness, and that their humanness—the way their minds and emotions have adapted to their social world—has shaped their interpretation of the divine. For that matter, so did the early Christians. The men and women who met in small, secret house groups to worship their god believed that the divine was inherently unknowable by human beings, whose human eyes and ears and hands are made to sense a mundane world. They took for granted that what they perceived was profoundly limited. This is the point of Paul's famous caution, in the stately translation that has echoed down the centuries:

For now we know in part, and we prophesy in part. 
But when that which is perfect is come, then that which is in part shall be done away.
When I was a child, I spake as a child, I understood as a child;
 but when I became a man, I put away childish things.
For now we see through a glass, darkly, but then face to face: now
I know in part, but then shall I know even as also I am known.

We will not see God clearly, Paul says, until we no longer see with human eyes. This is why Kierkegaard could describe the decision to believe as a leap in the dark, as a choice founded not on evidence but on the way we choose to live in the face of inadequate evidence. The fact of human uncertainty about the ultimate, and the stakes of our decision in the face of that uncertainty, are also why one can argue that no one is an adult until he or she has seriously considered the question of God.

Let me be clear: This book does not answer the question of whether God exists, or for that matter the question of whether God is truly present when someone experiences God as present. I am a social scientist, and I do not believe that social science—the study of the social life of humans—can answer those questions. I wrote this book because I think I can explain to nonbelievers how people come to experience God as real.

This is an important story because the rift between believers and non- believers has grown so wide that it can be difficult for one side to respect the other. Since evangelical Christianity emerged as a force in American culture, and especially since the younger George Bush rode a Christian wave into office, nonevangelical observers have been transfixed by the change in the American religious landscape. Many have been horrified by what they take to be naïve and unthinking false beliefs, and alarmed by the nature of this modern God.

It is indeed a striking God, this modern God imagined by so many American evangelicals. Each generation meets God in its own manner. Over the last few decades, this generation of Americans has sought out an intensely personal God, a God who not only cares about your welfare but worries with you about whether to paint the kitchen table. These Americans call themselves evangelical to assert that they are part of the conservative Christian tradition that understands the Bible to be literally or near literally true and that describes the relationship with Jesus as personal, and as being born again. But the feature that most deeply characterizes them is that the God they seek is more personally intimate, and more intimately experienced, than the God most Americans grew up with. These evangelicals have sought out and cultivated concrete experiences of God's realness. They have strained to hear the voice of God speaking outside their heads. They have yearned to feel God clasp their hands and to sense the weight of his hands push against their shoulders. They have wanted the hot presence of the Holy Spirit to brush their cheeks and knock them sideways.