H.E. Metropolitan Athanasios of Achaia graduated from the Department of Byzantine and Neohellenic Studies of the Faculty of Letters of the University of Athens (1972) and from the Faculty of Theology of the same University (1976). He got a license from the Oriental Institute in Rome (1978) and then followed a course in German language with a scholarship of the Ostkirchliche Institut in Regensburg. Later, he spent a year in Paris for studies in the Institut Catholique and the Sorbonne University and got a scholarship from the Catholic Church for three years (1977-1980). After that he got a D.Phil from the University of Oxford in 1984. Also he was the Keeper of Manuscripts of the National Library of Greece from 1983-1994. Between 1994-1997 he was professor of the Ecumenical Institute of Bossey. In 1997 he was appointed one of the first professors of the Institute of Higher Studies of Chambesy in Geneva, where he taught till 2000.
He was ordained as a deacon and then as a priest in 1991. He became bishop in 2000 and later he was promoted to the rank of a titular Metropolitan on August 31, 2007 retaining his title of Achaia. In 1998 he represented the Church of Greece to the 8th General Assembly of the World Council of Churches in Harare, Zimbabwe and also was a delegate of the Church of Greece at the 9th General Assembly of the WCC in Porto Alegre, Brasil. He participated in the official Anglican - Orthodox Dialogue as representative of the Orthodox Church of Albania and he was one of the members of the first official delegation of the Church of Greece to the Holy See in March 2002. He is a member of the Central Committee of the Conference of European Churches since 2003 and a member of the Mixed International Theological Committee on Dialogue between Orthodox and Roman-Catholics.
He has published several studies on the history of Christian faith and spirituality and speaks Greek, English, French and Italian