Osiander, Andreas (ändrāˈäs ōzēänˈdər) [key], 1498–1552, German reformer. His original name was Hosemann or Heiligmann. Ordained a priest in 1520, Osiander joined the cause of the Reformation in 1522. He supported Martin Luther vigorously, participating in the Marburg Conference (1529), the Diet of Augsburg (1530), and the signing of the Schmalkaldic Articles (1537). Frequently during controversies the coarseness and violence of his language aroused personal enmity. In 1548, Osiander's refusal to agree to the Augsburg Interim made it necessary for him to leave Nuremberg, and he joined the theological faculty at the new Univ. of Königsberg. Osiander's mystical interpretation of the Lutheran doctrine of justification by faith led to a disagreement with his colleagues that subsequently involved the whole German Evangelical Church.