Bartholomaeus Arnoldi

Bartholomaeus Arnoldi (usually called Usingen; ; 1465 – 9 September 1532) was an Augustinian friar and doctor of divinity who taught Martin Luther and later turned into his earliest and one of his personally closest opponents.

Life Usually called Usingen, after his birthplace, Arnoldi received his master's degree in 1491 and was promoted to the doctorate of divinity in 1514. For thirty years he filled the chairs of philosophy and theology at Erfurt University, and, with Jodocus Trutfetter, was its leading teacher. He enjoyed the favour of the younger humanists.

His anti-Reformation attitude and utterances in the end embittered Luther, who attacked his old teacher. He moved to Würzburg, in 1526, and in 1530 accompanied Conrad von Thüngen, the Bishop of Würzburg, to the Diet of Augsburg. Returning, he died at Würzburg, on 9 September 1532.