To most people acquainted with Immanuel Kant and Martin Luther, their differences in philosophical and religious outlook prevent comparison on most levels. Nevertheless, it is in the idea of two realms of spiritual or moral renewal that they begin to speak similar language. More specifically, Luther's description of Christians living in two kingdoms, living the spiritual life of faith alongside their imperfections in daily life, is echoed in Kant's notion of the ethical and political commonwealths, where a society of people ruled by morality is put alongside the political realm where these same people must be ruled by law. Like Luther, Kant affirmed the presence of what he termed radical evil in human nature, but also believed that the morally renewed person would express goodness in society as well. This "tempered" optimism can be compared to Luther's conviction that faith would have a positive effect on the life of the believer, in spite of the inevitability of sin.
"The Rebirth of Luther's Two Kingdoms in Kant's Commonwealths,"
Journal for Christian Theological Research: Vol. 3
, Article 3.
Available at: https://digitalcommons.luthersem.edu/jctr/vol3/iss1998/3