John Rawls, a giant of modern political philosophy, worked throughout his career to articulate the theoretical foundations of liberalism. Almost against his will, Rawls has suggested that those foundations are entangled with, and fortified by, religious faith.
Liberalism has always staked its claim to govern on its superior rationality. The modern liberal tradition, with its premise of the natural freedom and equality of all, arose in the 17th century partly in response to the turmoil of Europe’s wars of religion. When John Locke set out in his first Letter concerning Toleration (1689) to demarcate the sphere of life that belonged to religion and the sphere that belonged to secular authorities, he relied on reason rather than religion to map the boundaries. In the 18th and 19th centuries, in the writings of Montesquieu, James Madison, John Stuart Mill, and others, liberalism forged an alliance with the commercial spirit, science, and democracy. These were the forces associated with progress, while religion was generally equated with reaction. In the 20th century, the liberal tradition faced the eruption of the forces of unreason in hideous secular forms—Nazism and communism—and defeated them. At the beginning of the 21st century, a threat to the liberal tradition has erupted again, this time drawing strength from religion.
Over the centuries, however, the liberal tradition has also drawn strength from religion. Locke viewed the law of reason—a moral law that he regarded as universal and objective—as an expression of God’s eternal order. He also argued that religion, no less than reason, taught toleration. In the 19th century, Alexis de Tocqueville argued that liberal democracy in America depended on the vitality of the people’s religious faith. Hegel sought to show that the liberal state is Christianity in secular and political form. Today, even as the United States wages a worldwide war against religiously inspired terrorism, religion remains a powerful force within America itself.