Born in Herbitzheim (Alsace), Ehrhard studied theology at Würzburg and Münster, being ordained as a priest in 1885, then received his doctorate of theology in 1888. From 1889 he served as a professor of dogmatics at the Roman Catholic seminary in Strasbourg. From 1892 to 1898 he was a professor of church history at the University of Würzburg, and afterwards held professorships in Vienna (from 1898), Freiburg (from 1902) and Strasbourg (from 1903), where in 1911/12 he served as university rector. From 1920 to 1927 he was a professor of church history at the University of Bonn.[1][2]
Die altchristliche Literatur und ihre Erforschung seit 1880 (1894) – Early Christian literature and its research since 1880.
Die altchristliche Litteratur und ihre Erforschung von 1884-1900 (1894) – Early Christian literature and its research from 1884 to 1900.
Forschungen zur hagiographie der griechischen kirche, vornehmlich auf grund der hagiographischen handschriften von Mailand (1897) – Research involving the hagiography of the Greek church.
Der Katholizismus und das zwanzigste Jahrhundert im Lichte der kirchlichen Entwicklung der Neuzeit (1902) – Catholicism and the twentieth century in the light of ecclesiastical development in the modern age.
Die Griechischen Martyrien (1907) – The Greek martyrs.
Das Mittelalter und seine kirchliche Entwickelung (1908) – The Middle Ages and ecclesiastical development.
Urchristentum und Katholizismus : drei Vorträge (1926) – Early Christianity and Catholicism: three lectures.
Das Christentum im Römischen Reich bis Konstantin (1932) – Christianity in the Roman Empire prior to Constantine the Great.[3]
Die Kirche der Märtyer; ihre Aufgaben und ihre Leistungen (1932) – The church of the martyrs.
Urkirche und Frühkatholizismus (1935) – The early Church and early Catholicism.[4]
