6 O. Your memory has served you, and you have certainly given us at great length many quotations from the sacred books: but after going all round the wood, you are caught in my hunting-nets. Let the case be as you would have it, that an Arian bishop is the enemy of Christ, let him be the salt that has lost its savour, let him be a lamp without flame, let him be an eye without a pupil: no doubt your argument will take you thus far— that he cannot salt another who himself has no salt: a blind man cannot enlighten others, nor set them on fire when his own light has gone out. But why, when you swallow food which he has seasoned, do you reproach the seasoned with being saltless? Your Church is bright with his flame, and do you accuse his lamp of being extinguished? He gives you eyes, and are you blind? Wherefore, I pray you, either give him the power of sacrificing since you approve his baptism, or reject his baptism if you do not think him a priest. For it is impossible that he who is holy in baptism should be a sinner at the altar.
L. But when I receive a lay penitent, it is with laying on of hands, and invocation of the Holy Spirit, for I know that the Holy Spirit cannot be given by heretics.
O. All the paths of your propositions lead to the same meeting-point, and it is with you as with the frightened deer— while you fly from the feathers fluttering in the wind, you become entangled in the strongest of nets. For seeing that a man, baptized in the name of the Father and the Son and the Holy Ghost, becomes a temple of the Lord, and that while the old abode is destroyed a new shrine is built for the Trinity, how can you say that sins can be remitted among the Arians without the coming of the Holy Ghost? How is a soul purged from its former stains which has not the Holy Ghost? For it is not mere water which washes the soul, but it is itself first purified by the Spirit that it may be able to spiritually wash the souls of men. “The Spirit of the Lord,” says Moses, “moved upon the face of the waters,” from which it appears that there is no baptism without the Holy Ghost. Bethesda, the pool in Judea, could not cure the limbs of those who suffered from bodily weakness without the advent of an angel, and do you venture to bring me a soul washed with simple water, as though it had just come from the bath? Our Lord Jesus Christ Himself, of whom it is less correct to say that He was cleansed by washing than that by the washing of Himself He cleansed all waters, no sooner raised His head from the stream than He received the Holy Ghost. Not that He ever was without the Holy Ghost, inasmuch as He was born in the flesh through the Holy Ghost; but in order to prove that to be the true baptism by which the Holy Ghost comes. So then if an Arian cannot give the Holy Spirit, he cannot even baptize, because there is no baptism of the Church without the Holy Spirit. And you, when you receive a person baptized by an Arian and afterwards invoke the Holy Ghost, ought either to baptize him, because without the Holy Ghost he could not be baptized, or, if he was baptized in the Spirit, you must not invoke the Holy Ghost for your convert who received Him at the time of baptism.
Source: The Dialogue Against the Luciferians (New Advent)