Joseph (Josse) Marie Honoré Charles Mertens de Wilmars was a Belgian lawyer, a barrister in Antwerp, cofounder of the Christian democratic party CVP/PSC, one of the first assessors of the Conseil d’État in Brussels, for six years a representative in the Belgian Chamber, and a professor and curator at the Catholic University of Louvain. He was also one of the first justices of the European Court in Luxemburg, over which he presided from 1980 to 1984. The main sources for this article have been an excellent study made by Vera Fritz about the first members of the European Court of Justice, the memoirs of Josse Mertens de Wilmars, a long interview with him conducted by researchers of the University of Leuven, the political archives he left to the same institution, his publications, and some of my own recollections. He was a keen jurist and lawyer and a devout Christian in daily life. Was his influence dictated by his faith? There is no precise method to measure the action of the Holy Spirit in the development of law and institutions. We will let the reader judge.