Leibniz was a Lutheran. Yet, upon consideration of certain aspects of his philosophical theology, one might suspect that he was a Lutheran more in name than in intellectual practice. Clearly Leibniz was influenced by the Catholic tradition; this is beyond doubt. However, the extent to which Leibniz was influenced by his own Lutheran tradition—indeed, by Martin Luther himself—has yet to be satisfactorily explored. In this essay, the views of Luther and Leibniz on the non-cognitive component of faith are considered in (...) some detail. According to Luther, the only non-cognitive aspect of faith worth favoring is trust (fiducia), since it is trust in God’s promise of mercy that warrants justification for the sinner. Leibniz, for his part, sides with the Thomistic tradition in emphasizing love (caritas) as the non-cognitive element of faith par excellence. I argue that Leibniz falls into a trap forewarned by Luther himself, even if Leibniz had systematic metaphysical reasons for his disagreement. (shrink)