And step by step, since time began, I see the steady gain of man.
When John Greenleaf Whittier wrote these lines, he believed, with most of his 19th Century fellow optimists, that mankind was slowly but surely working its way through history to a better world. Science, statecraft and scripture, they thought, were leading men together to the same goal—the establishment of God's kingdom upon earth.
Today, midway in a bloodier, more dangerous century, there is widespread skepticism about "the steady gain of man." Most notable spokesman for this view among U.S. Protestants is Theologian Reinhold Niebuhr. In his newest book, Faith and...