He received his religious training at La Sarte, a Dominican Study house near Huy (Belgium), and Louvain University.
Then, on 14 June 1973, he was appointed titular archbishop of Lorium and secretary of the Congregation for the Doctrine of the Faith.
In 1974, the Congregation published a "declaration on procured abortion", re-asserting the Church's opposition to the controversial procedure since the publication of Humanae Vitae.
He became Prefect of the Congregation when he was made Cardinal-Deacon of San Saba in the consistory of 25 May 1985, two days after which the full title was formally granted him.
He opted for the order of Cardinal Priests after ten years and his deaconry was elevated pro hac vice to title on 29 January 1996.