Vier Bücher vom wahren Christentum (True Christianity)
Vier Bücher vom wahren Christentum
Das wahre Christentum bestehet nicht in Worten oder äußerlichem Schein, sondern in lebendiger Kraft.
Our renderingTrue Christianity consists not in words or outward show, but in living power.
What it is
Johann Arndt's masterwork of Lutheran devotional piety, published in four books between 1605 and 1610, is widely regarded as the most important Protestant devotional work between Luther's catechisms and the emergence of Pietism. It emphasizes repentance, genuine faith, the inner spiritual life, and living union with Christ, drawing on medieval mystics such as Tauler and Thomas à Kempis while remaining firmly within Lutheran soteriology. It was the direct inspiration for Philipp Jakob Spener's Pia Desideria and for the Halle Pietist program that shaped the Hohenzollern court under Frederick William I, who patronized Francke's orphanage schools where the book was a staple text. Translated into some thirty languages, it served for two centuries as the standard devotional companion to the Bible in devout German Protestant households.
Why it still matters
Available in modern English translation in the Paulist Press Classics of Western Spirituality series; its meditations on union with Christ and daily repentance work well as structured chapter-by-chapter devotional reading alongside the Small Catechism for a grounded Lutheran spiritual discipline.
Kept alongside
Brandenburg Church Order of 1540
Kirchenordnung der Kurmark Brandenburg (1540)
Personally commissioned by Elector Joachim II as the formal constitution of Lutheran worship for the Brandenburg electorate, this Kirchenordnung regulated all liturgy, sermons, baptism, communion, confession, and daily prayers in Brandenburg churches. Drafted by Berlin provost Georg Buchholzer and Jakob Stratner — dispatched from the Ansbach court of Margrave Georg of Brandenburg-Ansbach — it drew on the Nuremberg-Ansbach church order of 1533 and received review by Luther and Melanchthon before printing in mid-1540. It governed the devotional and liturgical life of all Hohenzollern-ruled Brandenburg for a generation, remaining in effect until its revision under Elector Johann Georg in 1572. Its issuance triggered systematic parish visitations across the Mark Brandenburg to enforce the new Protestant order.
Confession of Sigismund (Brandenburg Confession)
Confessio Sigismundi / Confessio Marchica
Issued on 10 May 1614 following Elector John Sigismund's public reception of Reformed communion on Christmas Day 1613, this personal confession of faith marked the Hohenzollern dynasty's formal turn from Lutheranism to Calvinism. It affirmed the four ecumenical creeds and the Altered Augsburg Confession of 1540, adopting a deliberately moderate and unionistic Reformed stance that omitted absolute predestination to avoid alienating Lutheran subjects. Although violent popular resistance in 1615 forced John Sigismund to abandon any attempt to impose Reformed practice on his subjects, the Confession gave the dynasty's court chapel and theological formation a distinctly Reformed cast for two centuries. Its irenic spirit prefigured the Lutheran-Reformed Prussian Union of 1817 and exercised lasting symbolic weight in Hohenzollern dynastic identity.
Luther's Small Catechism
Der Kleine Katechismus
Written in 1529 as a household guide for fathers to teach their children the essentials of Protestant faith, the Small Catechism covers the Ten Commandments, Apostles' Creed, Lord's Prayer, Baptism, the Lord's Supper, and daily prayers in a question-and-answer format designed for memorization. Duke Albrecht von Hohenzollern commissioned its translation into Old Prussian in 1545, printed by Hans Weinreich in Königsberg — the oldest printed books in that language — making vernacular catechetical instruction a cornerstone of the duchy's Reformation. Frederick the Great's 1763 General-Land-Schul-Reglement explicitly mandated Luther's Small Catechism in all Prussian schools, cementing it as the primary doctrinal formation text for Hohenzollern subjects across three centuries. It remains the most widely used Protestant catechism in the world and a living document in Lutheran congregations globally.