World-weary and worldly-wise, John Updike is in his winter years. He's lost his boyish look of shy awkwardness. He still has the thin skewed smile, as if waiting for a schoolroom prank to come off, but he's wizened and ashen now. There's a shadow of caution in his eyes.

At 70, he's well established among élite U.S. writers. His latest novel, Seek My Face (Alfred A. Knopf, 2002), comes atop a massive oeuvre and a wall-full of prestigious literary awards, including a Pulitzer. But he's not won a Nobel to complete his crown, and likely won't. His best work is probably behind him. His detractors think not even that much: that he never produced anything that lived up to the flawed but dazzling promise of his early accomplishments.

And then there's the sex. Updike is notorious for his novelistic randiness. Most people who've never read him know him as that man who writes dirty books. And, to be sure, some of his novels—Couples, Roger's Version, A Month of Sundays—seem only thinly disguised excuses to parade the gaudy excess of America's sexual fetishes. Even when you know he's up to something else—that his sexual explicitness has a cultural critique, even a theological agenda, behind it—it's pretty hard to stomach.

Still, Updike is rare among his ilk. He is, if not a "Christian" novelist, certainly North America's most theological one. Nearly his entire life's work is concerned with theological questions, and a good number of his works hinge on these. How many other contemporary authors could—or would—bandy about the theology of Barth, Tillich, or Bultmann in their novels? Or have page after page of dialogue between characters working out intricate doctrinal positions? Updike does this repeatedly and with discernment.

He also does ...