Arnold was born in Königsberg, East Prussia, Germany, the third child of Carl Franklin and Elizabeth (Voight) Arnold. His father was a doctor of theology and philosophy, and his paternal grandfather was a pastor and missionary of the Evangelical State Church of Prussia's older Provinces. Eberhard Arnold's life as a youth was unconventional. In 1899 at age 16, Arnold experienced an inner change, which he acknowledged as God's acceptance and the forgiveness of sins, and felt a calling to "go and witness to my truth."