Peter De Mey

This article by Peter De Mey examines the role of non-Catholic observers at the Second Vatican Council (1962-1965), drawing on unpublished archives, including transcripts of weekly meetings held at the Centre Lumen Gentium in Louvain-la-Neuve. Belonging to the genre of historical and theological study, the contribution first traces the diplomatic conditions that made it possible to invite Protestant, Orthodox, and Anglican observers, then analyzes their concrete influence on the drafting of Lumen Gentium and Unitatis Redintegratio. The main argument is that these observers, far from being mere silent witnesses, formulated substantial theological critiques — on pneumatology, justification, and comparative ecclesiology — that shaped the conciliar texts. The article's contribution lies in its documented demonstration that Vatican II constitutes a significant historical precedent for ecumenical participation in a council, thereby offering a reference model for the Pan-Orthodox Holy and Great Council.