Demetrios was born in
Thessaloniki, Greece on 1 February 1928 to Georgia and Christos Trakatellis. He graduated in 1946 valedictorian from the Experimental School of the University of Thessaloniki. He attended the School of Theology at the
National and Kapodistrian University of Athens, graduating
summa cum laude in 1950. He became a deacon in 1960 and was ordained as a priest in 1964. He moved to the United States in 1965, attending the
Harvard Graduate School of Arts and Sciences and obtaining his PhD in 1972. He later returned to the University of Athens, obtaining his
Doctor of Theology degree in 1977. He served as auxiliary bishop to the Archbishop of Athens from 1967, and in 1968 declined to serve as
Metropolitan of
Attika and
Megaris due to the political upheaval then taking place in Greece. He was Distinguished Professor of Biblical Studies and Christian Origins at
Hellenic College Holy Cross Greek Orthodox School of Theology in Brookline, Massachusetts, from 1983 to 1993, and was a visiting professor at
Harvard Divinity School in 1984–85 and 1988–89. He returned to Greece in 1993 to serve at the
Greek Orthodox Archdiocese of Athens. The cathedral on New York City's
Upper East Side serves as the national cathedral of the Greek Orthodox Archdiocese of America and is the seat of the Archbishop. On 26 November 2015, the
Greek Orthodox Archdiocese of America was elevated to the rank of Gerontiki Eparchy (an eparchy headed by a Geron/Elder hierarch) of the Ecumenical Throne, led by Demetrios, with the style of His Eminence Geron Archbishop Demetrios of America. ==Academy and Holy Synod==