Final answer:
The bishop's throne in an early Christian church is known as a cathedra, which also denotes the bishop's authority and is the origin of the word 'cathedral.'
Step-by-step explanation:
The bishop's throne in an early Christian church is called a cathedra. This term has also come to indicate the authority of a bishop, particularly in reference to the bishop of Rome who later became known as the pope. The cathedra symbolizes the bishop's role as a teacher and shepherd of his flock, and it is from this term that we also derive the word "cathedral," which is the primary church of a bishop's diocese. In early Christian churches, especially in Byzantine architecture, the bema often served as the sanctuary where the altar was located and the clergy, including bishops, led the celebration of the Eucharist. This area, separated from the main part of the church or naos, was a focal point for liturgical rites.