Background
He was born at Kitzingen, Bavaria, the son of a fisherman, attended school in Kitzingen, and from 1709 to 1715 studied at the Jesuit College at Würzburg.
He was born at Kitzingen, Bavaria, the son of a fisherman, attended school in Kitzingen, and from 1709 to 1715 studied at the Jesuit College at Würzburg.
In 1715 he entered the seminary of the latter city and in 1721 was ordained priest. Christopher von Hutten, Prince-Bishop of Würzburg, sent him, in 1725, to Rome to study ecclesiastical law under Prosper Lambertini, later Pope Benedict XIV. Barthel returned as Doctor Utriusque Juris, in 1727, to Würzburg, where he became president of the seminary and (1728) professor of canon law at the university. Other ecclesiastical and academical honours, among them the vice-chancellorship of the university (1754), were conferred upon him.
He took an active part in settling the controversy occasioned by the erection of the new Diocese of Fulda (1752).
He broke with the traditional method in canonical science, being one of the first to adopt the historico-critical treatment in Germany. His efforts to distinguish between the essentials and non-essentials in Catholic doctrines, and his attribution of excessive power to the State in its relations with the Church caused his opinions to be denounced at Rome as unorthodox.