He was professor of Fundamental Theology at the University of Münster from 1963 to 1993, where he developed a Theology after Auschwitz (Holocaust theology). He introduced philosophical and political ideas of 1968, by Ernst Bloch and the Frankfurt School of Max Horkheimer and Theodor W. Adorno, in theology, which was received with opposition. His concepts were applied by the liberation theology in Latin America. He participated in the founding of the University of Bielefeld, and was a leading member of the international Paulus-Gesellschaft dedicated to a dialogue of Christianity and Marxism. After the Second Vatican Council, he was a consultant of the papal secretariate for the "noncredentibus" from 1968 to 1973. Metz was a consultant of the Würzburg Synod of the German dioceses from 1971 to 1975, and was the principal author of its document "Unsere Hoffnung" (Our hope) which became a key document for the reception of the Second Vatican Council in Germany.