He was one of the representatives of the Orthodox Church of Greece that participated in the World Council of Churches: in Amsterdam (1948),[REF] in Evanston, Illinois, United States (1954),[REF] as well as in New Delhi, India (1961) [REF].
In a number of reports about the Second Vatican Council (1962) Ioannidis addressed the importance of such an event, although the results of this, according to him, did not change the relations between the Roman Catholic and the Eastern Orthodox Church [REF].