Whoever honors the priest will honor God, and he who has learned to despise the priest will gradually proceed in time to insult God also. ‘He who receives you receives Me.’ [Mt. 10:40]. And it is written, ‘But hold His priests in honor.’ [Sir. 7:31]. Hence, the Jews learned to despise God because they despised Moses and would have stoned him [cf. 17:4]. And when someone acts reverently towards a priest, he will be much more reverent toward God. And even if a priest is wicked, God who is watching, will bestow a reward on you because you have shown reverence to him who is unworthy of honor in order to honor Him. ‘He who receives a prophet because he is a prophet shall receive a prophet’s reward.’ [Mt. 10:41], as it is written. ‘and whoever submits to and obeys the priest and honors him for the sake of the Lord will be blessed.’ The scribes and Pharisees sit on Moses’ seat, so practice and observe whatever they tell you, but no what they do; for they preach but do not practice.’ [Mt. 23:2-3].
Do you know, they say, what a priest is? He is an angel of the Lord. Surely he does not say things that are his own. if you despise him, you are not despising him but (you are despising) God Who has ordained him. And from whence does it appear that God ordained him? If you do not have this faith and reverence, your hope is rendered vain. For if God does not [allow divine grace to] work through an unworthy celebrant, you have neither washing [of baptism], nor do you participate in the sacraments, nor do you receive any blessings; and, therefore, you are not a Christian.
For what reason then does God ordain all, even the unworthy ones? God does not ordain all, but He works through all, even through they may be unworthy, in order that the people may be saved. For if He spoke for the sake of His people through a donkey, and through Balaam who was a wicked man [cf. Num. 22:21], how much more does He speak through the priest?
– Commentary on 2 Timothy 2:12, Homily V, NPNF s. 1, v. 13.