Journalist Christopher Hitchens is one of the world’s most famous atheists. His brother, Peter, insists that a civilized world must believe in God. The brothers have publicly argued over faith for years. But now that Christopher Hitchens has been diagnosed with cancer, the theoretical argument has become real.

Just how real was apparent at the Pew Forum on Religion and Public Life, where the brothers were having a public conversation about God.

Christopher Hitchens often wears a white straw hat. He says his head, completely bald from chemotherapy treatments, gets cold. He’s tired. He’s thin. He’s off his food.

But ask Hitchens, author of God Is Not Great, if having cancer has changed his view of religion or God.

“If anything, my contempt for the false consolation of religion has increased since I became aware that I probably don’t have very long to live,” he replies.

Since Hitchens’ cancer diagnosis in June, he has received thousands of letters and e-mails, some from believers asserting that he’s getting what he deserves, more from people saying they’re praying for his recovery. Hitchens says he has been overwhelmed by the outpouring. But he is annoyed that some writers hope he’ll have a last-minute conversion to Christianity.

“Under no persuasion could I be made to believe that a human sacrifice several thousand years ago vicariously redeems me from sin,” he says. “Nothing could persuade me that that was true — or moral, by the way. It’s white noise to me.”

His brother, Peter, is equally blunt: “There is actually no absolute right or wrong if there is no God,” he says.

Peter once shared his older brother’s views; he burned his Bible when he was a teenager in boarding school. But as he chronicled in his book, The Rage Against God — which he wrote as a response to his brother’s anti-religious book — he felt drawn back to his Anglican faith starting in his late 20s.

He says his work as a journalist in Somalia and the former Soviet Union convinced him that civilization without religious morality devolves into brutality. Moral behavior requires more than higher reasoning, he says; it requires God.

“It seems to me to be very, very, very hard to come up with an atheistic explanation of conscience any more than you can have a compass with a magnetic north,” he says. “If the magnetic north kept shifting, then it would be very difficult to steer your boat or your plane across the Atlantic.”

Christopher Hitchens dismisses that argument — pointing out that much of the world’s evil is committed in the name of religion.

“If I was to say to someone, ‘Now, can you name me please a hideous moral act undertaken or an immoral remark made because of their faith?’ You’ve already thought of one. Now you’ve thought of another one. You’ll keep on thinking of them.”

Of course, Peter says arguments like that overlook all of the good that religion has done.

The Hitchens brothers have fought over God — with barely concealed disdain — for years. But now the tone feels different.

“I really don’t see the point in spoiling a good argument by getting angry with your opponent,” Peter Hitchens says. “And he has been my opponent for most of my life. I certainly have in the past been angry with him. But I would say that that is over.”

For his part, Christopher Hitchens praised his brother’s book and laughed at his jokes. As for facing death, he suspects that you have the same emotions, whether or not you believe in God.

“People say, ‘Cancer picked the wrong foe in you — you can beat this if anyone can,’ lots of that kind of thing, and it has the effect of kind of giving me the blues because I don’t want to let people down. The psychological makeup of this is roughly the same whether you assume a supernatural dimension or not,” he says.

Still, Christopher Hitchens’ bout with cancer is remarkable in one respect. He has chosen to confront the biggest questions — about God, life and death — in the most public of ways. Copyright 2010 National Public Radio. To see more, visit http://www.npr.org/. Copyright 2010 National Public Radio. To see more, visit http://www.npr.org/.