After receiving his diaconate, Dn. Anastasios formed the inter-Orthodox mission center “Porefthentes” with the aim of educating the church in the area of missions. O 1964, Dn. Anastasios was ordained a priest and left for East Africa to celebrate his first liturgy in Uganda. However, soon Fr. Anastasios came down with malaria and had to return to Greece. With the doctors recommending his not returning to Africa, Fr. Anastasios decided to influence the church about the work of mission through the academic world. In preparation, Fr. Anastasios turned to postgraduate studies in history of religion including ethnology, science of religions, missiology and African studies. In this pursuit, he studied at universities in Hamburg and Marburg, with research work at the Makerere University in Uganda to collect material for his doctoral thesis “The Spirit Mbandwa and the Framework of Their Cults: A Research of Aspects of African Religion ». Furthering his work in missions, Bp. Anastasios, with Fr. Anthony Romeos, founded a monastery of nuns, the Convent of St. John the Forerunner, in Kareas, Greece, that would participate in missionary work throughout the world.
In 1980, Bp. Anastasios was asked by Patriarch Nicholas of the Church of Alexandria to take on reinvigorating the Archdiocese of East Africa. In addition to his responsibilities at the University of Athens and with the Apostoliki Diakonia, Bp. Anastasios consented. A particularly acting archbishop during this transitional period, Abp. Anastasios worked to create a strong Orthodox community through training and establishing indigenous leaders. In 1982, he re-opened the Orthodox seminary in Nairobi that Abp. Makarios III of Cyprus had founded ten years before but remained incomplete because of political instability in Cyprus. Over the next ten years Abp. Anastasios ordained sixty two indigenous priests and deacons and forty-two readers and catechists from the graduates of the seminary. These clergy provided the foundation for the renewal of the church in East Africa. By the time he departed Africa in 1991, he left a legacy through his efforts to assimilate with the indigenous Christians and empower them to embrace Orthodoxy as their own.
In 1991, following the fall of the communist government of Albania and the ensuing political changes, Abp. Anastasios was appointed by the Ecumenical Patriarch Bartholomew I to be the Patriarchal Exarch for the Albanian Church with the mandate to re-establish the Autocephalous Church of Albania without regard to the ethnic origin of its people. He was named Archbishop of Tirana on June 24, 1992 and enthroned on August 2, 1992. For this challenge, Abp. Anastasios drew on his academic work and field accomplishments in East Africa to establish the structure to train local leaders. Under his leadership, the church opened a seminary with more than eighty students and within two years increased the Albanian clergy from eleven to fifty six.