Why do we address Bishops as Rabbi “My lord”? While we have one Lord God. Who said: “But you, do not be called ‘Rabbi’; for One is your Teacher, the Christ, and you are all brethren”. (Mat 23:8)
The Lord Jesus uttered these words to criticise the pride of the pharisees and the scribes.
(Mat 23:6-8) “They love the best places at feasts, the best seats in the synagogues, “greetings in the marketplaces, and to be called by men, ‘Rabbi, Rabbi.’ “But you do not be called ‘Rabbi’; for One is your Teacher, the Christ, and you are all brethren.
By saying the above verse, Jesus wanted to abolish the leadership and control of the Scribes and Pharisees, who were focused on self glory in preparation for the new church leadership.
He said this to His disciples only and not to the general public. He commanded His disciples not to call anyone father or teacher since the disciples and their successors were to become the fathers and teachers of all. The lordship and superiority of the priesthood does not contradict humility
“For a bishop must be blameless, as a steward of God, not self-willed, not quicktempered, not given to wine, not violent, not greedy for money” (Titus 1:7)
Hence the lordship is for the purpose of order in the church and it not a form of suppression of others as was the case with the Scribes and the Pharisees. (From: H.H. Pope Shenouda, On Priesthood)