Charles Darwin was nothing if not methodical. When the time came to consider marriage, he divided a sheet of paper into two sections, "Marry" and "Not Marry." Under the first heading he noted: "a friend in old age ... better than a dog anyhow." In the second he tallied counterarguments: "perhaps quarreling," he fretted, and "less money for books."

Darwin's commitment to weighing the facts would be welcome in the modern world that celebrated the great naturalist's 200th birthday this week. While Darwin himself never took his findings about evolution as definitive evidence against the existence of God, many people of faith have read that conclusion into his work. As a result, the man who first grasped biology's most unifying concept is today widely demonized as an enemy of the church.

Darwin was a mostly Anglican biblical literalist when he set sail on his famed voyage aboard the Beagle. He believed that God created the world as it is, with all its countless species intact from the start. But Darwin's studies of rocks and fossils opened his eyes to the immensity of geologic time. And his keen observation of life's variations and adaptations sowed the seeds of his eventual revelation that mutation and natural selection, acting on simpler forms of life, could account for all biological diversity.

Darwin's basic insight threatened some conventional religious beliefs, of course. If we humans shared a common ancestry with apes -- and if we got here by dint of the same trial-and-error slog as every other species on Earth -- then so much for our being God's favorites, lovingly crafted in his image. And, yes, over time Darwin rejected a literal reading of the Bible, concluding that, as a history text, it was "no more to be trusted than the sacred books of the Hindoos, or the beliefs of any barbarian."

But Darwin also recognized that his vaunted theory of evolution was dumb on the all-important question of creation -- the mystery of what set the universe in motion.

As with matrimony, Darwin rigorously considered the matter. On the positive side, it certainly felt like something divine was afoot. But he appreciated that this was a subjective and perhaps untrustworthy measure. The "immense amount of suffering through the world" -- not least of which his own, highlighted by the death of his 10-year-old daughter -- argued against a benevolent creator, he wrote (with Facebook-like fanaticism, he maintained a correspondence with some 2,000 friends, including 200 clergymen). At the same time, he hedged, it seemed foolish to reject the assertions of so many intellectually "able men" who "fully believed in God."

In the end, he did what any reasonable person might do: He punted. "The safest conclusion seems to be that the whole subject is beyond the scope of man's intellect," Darwin concluded. "Every man," he wrote, "must judge for himself, between conflicting vague probabilities."

Darwin's humility in the face of insufficient evidence -- his willingness to say "I don't know" -- is as important a lesson as any to be found in biology texts today.

Soldiers in today's culture wars, whether in black collars or white lab coats, could take a tip from Darwin on his birthday bicentennial. He loved the natural world, "most beautiful and most wonderful." And he knew enough to not pick fights over what he did not know.

Rick Weiss, a senior fellow at the Center for American Progress, wrote this article for the Washington Post.