Bestselling atheist author Christopher Hitchens showed plenty of spunk and energy in a debate tonight in Birmingham despite undergoing recent chemotherapy for esophageal cancer.

Hitchens, author of "God is Not Great: How Religion Poisons Everything," defended atheism as a moral stance in a debate attended by about 1,200 at the Birmingham Sheraton Hotel with David Berlinski, author of "The Devil's Delusion: Atheism and Its Scientific Pretensions."

Berlinksi argued that it is atheism, not religion, that poisons society.

"Atheism leaves unanswered the question, 'What obliges us, what forces us, to behave as we should?'" Berlinski said.

As he has been battling cancer this year, Hitchens has canceled nearly all his public appearances, including a book tour to promote his new memoir, "Hitch-22."

Fixed Point Foundation, sponsor of the debate, had brought Hitchens to Birmingham last year to debate Christian apologist John Lennox at Samford University.

Larry Taunton, executive director of Fixed Point Foundation, said that Hitchens insisted on keeping his commitment to appear in Birmingham again.

Hitchens, a popular speaker and writer for Vanity Fair and other magazines, drew loud applause throughout the debate.

Berlinski, a mathematician who lives in Paris, described himself as a secular Jew who defends the religious worldview because of its moral imperatives that he finds lacking in atheism.

When Berlinski linked Nazism and Darwinism while connecting atheism with violent government regimes of the 20th Century, Hitchens bristled and went on the attack in his next turn at the podium.

Connecting Nazism with Darwinism "is a filthy slander," Hitchens said. "Darwinism was derided in Germany."

Hitchens said Adolf Hitler claimed in "Mein Kampf" that he was doing God's work with his policies against the Jews and that the first Nazi treaty was with the Vatican.

"To say that there is something fascistic about my beliefs, I won't hear said, and you shouldn't believe," Hitchens said to the audience, almost thundering despite his diminished voice.

Berlinski responded that fascist and Communist governments including Nazi Germany and Soviet Russia held in common the proposition that "No power was greater than their own, and they acted on that." They were godless governments, despite some "infiltrations of religious thought," he said.

Taunton said he drove Hitchens to Birmingham this week from the Washington, D.C., area, and had Hitchens read aloud the prologue of the Gospel of John, which they then discussed.

Hitchens referred to that in the debate, saying that if Taunton found out Jesus did not exist, it would ruin his life.

Taunton responded at the end of the debate. "It would ruin my life," he said. "It would suggest this life is a sham."

Hitchens shook his head. "Don't give up so easily," he said.

Taunton said the debate was taped by C-Span, which will be airing it soon. A crew from "60 Minutes" was also present, he said.

At a luncheon earlier in the day with Hitchens and Berlinski, Taunton asked Hitchens about his health problems. "Well, I'm dying, since you asked," Hitchens replied. "So are you, but I'm doing it faster and in more rich and fecund detail."

Hitchens, who has lost his hair since he debated Lennox in Birmingham last year, said he is in his fourth course of chemotherapy and it has shrunk the tumors. Hitchens said he continues to write and hopes to do a book about the Ten Commandments.

Berlinski said he has been writing books countering the arguments made by aggressive atheists because he became irritated "by various blowhards in the scientific community."