September 5, 1666, Annaberg, Erzgebirge, Saxony.
May 30, 1714, Perleberg, Brandenburg, Germany.
Son of the local schoolmaster, Gottfried in 1682 went to the Gymnasium at Gera, and three years later to the University of Wittenberg. There he studied theology and history, and afterwards, through the influence of Philip Jacob Spener, the father of pietism, became a tutor in Quedlinburg.
His first work, Die Erste Liebe zu Christo, appeared in 1696. It went through five editions before 1728, and gained Arnold a high reputation. In the year after its publication he was invited to Gießen as professor of church history. But he disliked academic politics and academic life so much that he resigned in 1698, and returned to Wittenberg.
The next year Arnold began to publish his largest work, his Unparteyische Kirchen- und Ketzer-historie (Impartial History of the Church and of Heresy) (Frankfurt: 1699–1700), two hefty volumes in which some thought he showed more sympathy towards heresy than towards any established Church, or especially the clergy. This book is described by Leo Tolstoy (The Kingdom of God Is Within You, chapter 3) as
remarkable, although little known.
In this major revision of church history, Arnold directed his sharpest criticism against those who wrote what he saw as biased apologetic
orthodox histories instead of trying to understand where substantial religious differences actually came from. In his view,
heresy making was usually the defensive reaction of those in authority, rather than a true indictment of unconventional thinkers. He thought that the worst calamity in Church history was its establishment as the accepted and orthodox faith by the Roman Emperor Constantine in the 4th Century. Arnold evinced a remarkable sympathy for a huge variety of
heretics. His book exercised a wide influence on the German Enlightenment and won approval from such thinkers as Johann Wolfgang Goethe in addition to Tolstoy.
His next work, Geheimniss der göttlichen Sophia, showed Arnold had developed a form of mysticism including a female image of wisdom as a kind of divinity. Soon afterwards, however, his marriage and his acceptance of a pastorate marked a sharp change of views, and he produced a number of noteworthy works on practical theology. He was a thoroughly learned and prominent Pietist Lutheran, with a wide range of influence, and at least in his early career a radical Pietist, vehemently opposed to the unbending ecclesiastical structures of his time.