9 O. I do not deny that it is the practice of the Churches in the case of those who living far from the greater towns have been baptized by presbyters and deacons, for the bishop to visit them, and by the laying on of hands to invoke the Holy Ghost upon them. But how shall I describe your habit of applying the laws of the Church to heretics, and of exposing the virgin entrusted to you in the brothels of harlots? If a bishop lays his hands on men he lays them on those who have been baptized in the right faith, and who have believed that the Father, Son, and Holy Ghost, are three persons, but one essence. But an Arian has no faith but this (close your ears, my hearers, that you may not be defiled by words so grossly impious), that the Father alone is very God, and that Jesus Christ our Saviour is a creature, and the Holy Ghost the Servant of both. How can he then receive the Holy Ghost from the Church, who has not yet obtained remission of sins? For the Holy Ghost must have a clean abode: nor will He become a dweller in that temple which has not for its chief priest the true faith. But if you now ask how it is that a person baptized in the Church does not receive the Holy Ghost, Whom we declare to be given in true baptism, except by the hands of the bishop, let me tell you that our authority for the rule is the fact that after our Lord's ascension the Holy Ghost descended upon the Apostles. And in many places we find it the practice, more by way of honouring the episcopate than from any compulsory law. Otherwise, if the Holy Ghost descends only at the bishop's prayer, they are greatly to be pitied who in isolated houses, or in forts, or retired places, after being baptized by the presbyters and deacons have fallen asleep before the bishop's visitation. The well-being of a Church depends upon the dignity of its chief-priest, and unless some extraordinary and unique functions be assigned to him, we shall have as many schisms in the Churches as there are priests. Hence it is that without ordination and the bishop's license neither presbyter nor deacon has the power to baptize. And yet, if necessity so be, we know that even laymen may, and frequently do, baptize. For as a man receives, so too he can give; for it will hardly be said that we must believe that the eunuch whom Philip baptized lacked the Holy Spirit. The Scripture thus speaks concerning him, “And they both went down into the water; and Philip baptized him.” And on leaving the water, “The Holy Spirit fell upon the eunuch.” You may perhaps think that we ought to set against this the passage in which we read, “Now when the apostles which were at Jerusalem heard that Samaria had received the word of God, they sent unto them Peter and John: who, when they had come down, prayed for them that they might receive the Holy Ghost: for as yet he was fallen upon none of them.” But why this was, the context tells us—“Only they had been baptized into the name of the Lord Jesus. Then laid they their hands on them, and they received the Holy Ghost.” And if you here say that you do the same, because the heretics have not baptized into the Holy Spirit, I must remind you that Philip was not separated from the Apostles, but belonged to the same Church and preached the same Lord Jesus Christ: that he was without question a deacon of those who afterwards laid their hands on his converts. But when you say that the Arians have not a Church, but a synagogue, and that their clergy do not worship God but creatures and idols, how can you maintain that you ought to act upon the same principle in cases so totally different?
L. You repel my attack in front with vigour and firmness: but you are smitten in the rear and leave your back exposed to the darts. Let us even grant that the Arians have no baptism, and therefore that the Holy Ghost cannot be given by them, because they themselves have not yet received remission of sins; this altogether makes for victory on my side, and all your argumentative wrestling is but laborious toil to give me the conqueror's palm. An Arian has no baptism; how is it then that he has the episcopate? There is not even a layman among them, how can there be a bishop? I may not receive a beggar, do you receive a king? You surrender your camp to the enemy, and are we to reject one of their deserters?
Source: The Dialogue Against the Luciferians (New Advent)