First, a quick definition of Calvin's view of the two kingdoms: "The spiritual kingdom of Christ and civil government are things very widely separated" (Institutes 4.20.1) The institutional expression of the former is the organized church.
I've been reading David Van
Drunen's book
Natural Law and the Two Kingdoms, in part out of personal interest and in part because there will be a seminary-wide discussion of the work. In his chapter on Calvin, Van
Drunen argues that Calvin's doctrine of the two kingdoms is somewhat at odds with his practice as it pertained to the city of Geneva. Assuming for the sake of argument that Van
Drunen is right, I think the explanation for the difference is clear. In the mid-sixteenth century, Geneva was a relatively small town of about 25,000 (see E. William
Monter, "Women in Calvinist Geneva [1550-1800],
Signs 6 [1980], 189). Even today the area of Geneva is only about 100 square miles, and would have been smaller in 1550. Thus it was a town that was religiously and ethnically homogeneous. In other words, in most demographic ways, Geneva was a unified town.
Furthermore, the history of Europe up to the time of the Reformation is a long history of church involvement in politics, and political involvement in church issues. It was one things for Calvin to posit a "two kingdoms" view in theory. It would have been almost impossible given the historical, theological, political, and demographic situation to have put that view into practice.
