The essays in Theological Tractates were published between 1925 and 1937, during which time Erik Peterson converted from Protestantism to Roman Catholicism. They deal with a range of theological topics-from the thought of Protestant theologian Karl Barth, to liturgy, the Church in the New Testament, Christianity and Judaism, angels, martyrdom, and mysticism. Among them is Peterson's landmark essay on ancient "political theology," "Monotheism...