Christian thinking famously articulated by Augustine in The City of God, developed in the Lutheran and Calvinist Reformations, and brought to greater maturity in the post-Reformation Reformed tradition.3 Many writers today seem to associate a two-kingdoms doctrine with unwarranted dualisms, secularism, moral neutrality in social life, or even the denial of Christ’s universal kingship. Perhaps some versions of the two-kingdoms doctrine have fit such stereotypes. My task in this book is not to defend