This is not liberation theology, with its assertion that God favors the oppressed, but it does echo the Social Gospel, the movement that a century ago called for Christianity to “add its moral force to the social and economic forces making for a nobler organization of society” with churches actively ameliorating “the burden of poverty,” in the words of the movement’s leader, Walter Rauschenbusch.

And yet Mr. Obama is also an admirer of Reinhold Niebuhr, the theologian who rejected what he considered the naïve moralism of the Social Gospel. From Niebuhr, Mr. Obama has said, he got the message “that there’s serious evil in the world, and hardship and pain. And we should be humble and modest in our belief we can eliminate those things.”

The tension between these two religious ideas — one wedded to progress, the other mindful of the limits of worldly activism — reflects the broader tension in Mr. Obama’s liberalism, itself divided between an enthusiasm for bold policy initiatives and a pragmatic understanding that some things can’t be fixed or even much changed through politics.

There is nothing unusual in this balance. It is the same one that any number of presidents, Republican and Democrat alike, have tried to maintain, whether reformers on the left like Franklin D. Roosevelt, or on the right like Ronald Reagan.