Lincoln grew into an intensely religious man, although we rarely hear him described in those terms nowadays. His religious faith became fundamental to his thinking and decision-making during the Civil War; we rarely hear that either. When he assumed the enormous burden of the presidency with war approaching, his faith grew deeper. When his beloved young son Willie died in early 1862, it deepened again—and seemed to continue growing deeper until his death. In the end Lincoln should almost certainly be remembered as the most important religious figure America has ever produced. I don’t mean he was a theologian. But Amos, Isaiah, and Jeremiah weren’t theologians either.

– David Gelernter, The Fourth Great Western Religion