The Holy Great Martyr Demetrius of Thessalonica was the son of the Roman proconsul in Thessalonica. His parents were secret Christians.
Dimitri had already reached the age of majority when his father died. Emperor Galerius Maximilian, who ascended the throne in 305, called the young man to himself and, convinced of his education and military administrative abilities, appointed proconsul of the Thessalonian region to his father's place. The main task entrusted to the young proconsul was to defend the city from barbarians and exterminate Christianity.
Having accepted the appointment, Demetrius, instead of persecuting and executing Christians, began to openly teach the inhabitants of the city the Christian faith and eradicate pagan customs and the worship of idols.