Bp. Thomas was enthroned as Bishop of Oakland and the East at St. George Cathedral in Pittsburgh (Borough of Oakland), Pennsylvania, on [[May 6]], 2005. In August of 2006, Bishop Thomas was awarded a Doctorate in Education from California Coast University. His Grace also sits on the editorial board of ''Christian Bioethics''.
In 2006, the Church of St. George in Charleston, West Virginia, purchased a chancery for the diocese, and in October of that year was elevated to a cathedral, thus adding another see to Bp. Thomas's the diocese and renaming it to the ''Diocese of Charleston, Oakland and the Mid-Atlantic''.
On February 24, 2009, by a decision of the Holy Synod of Antioch, Bp. Thomas was appointed as auxiliary to Metr. Philip.