John Arndt was a prominent German Lutheran theologian and mystic who lived from 1555 to 1621. Born in Ballenstedt, he pursued his academic studies at both Wittenberg and Helmstedt. Throughout his career, he held various roles including parson, court chaplain, and general superintendent in Celle. He is most notably recognized for his influential devotional literature and his role as a foundational figure for the Pietist movement, which emphasized personal piety and practical Christian living.