In his excellent new book The Intolerance of Tolerance (Eerdmans, 2012), D.A. Carson reflects on the popular idea that “citizens with moral values grounded in religious beliefs are forbidden to articulate those beliefs and vote for those values” (p. 105). He draws our attention to a speech by Abraham Lincoln, who critiques this notion with respect to slavery:

But those who say they hate slavery, and are opposed to it, . . . where are they?

Let us apply a few tests.

You say that you think slavery is wrong, but you denounce all attempts to restrain it. Is there anything else that you think wrong that you are not willing to deal with as wrong? Why are you so careful, so tender, of this one wrong and no other? You will not let us do a single thing as if it was wrong; there is no place where you will even allow it to be called wrong! We must not call it wrong in the free States, because it is not there, and we must not call it wrong in the slave States, because it is there; we must not call it wrong in politics because that is bringing morality into politics, and we must not call it wrong in the pulpit because that is bringing politics into religion . . . and there is no single place, according to you, where this wrong thing can properly be called wrong!

—Abraham Lincoln, “Speech at New Haven, Connecticut [1860],” in Lincoln: Speeches and Writings, 1859-1865 (New York: Library of America, 1989), 140-141.