21 But when it is said that "the Holy Spirit is given by the imposition of hands in the Catholic Church only, I suppose that our ancestors meant that we should understand thereby what the apostle says, "Because the love of God is shed abroad in our hearts by the Holy Ghost which is given unto us." For this is that very love which is wanting in all who are cut off from the communion of the Catholic Church; and for lack of this, "though they speak with the tongues of men and of angels, though they understand all mysteries and all knowledge, and though they have the gift of prophecy, and all faith, so that they could remove mountains, and though they bestow all their goods to feed the poor, and though they give their bodies to be burned, it profits them nothing." But those are wanting in God's love who do not care for the unity of the Church; and consequently we are right in understanding that the Holy Spirit may be said not to be received except in the Catholic Church.
For the Holy Spirit is not only given by the laying on of hands amid the testimony of temporal sensible miracles, as He was given in former days to be the credentials of a rudimentary faith, and for the extension of the first beginnings of the Church. For who expects in these days that those on whom hands are laid that they may receive the Holy Spirit should immediately begin to speak with tongues? But it is understood that invisibly and imperceptibly, on account of the bond of peace, divine love is breathed into their hearts, so that they may be able to say, "Because the love of God is shed abroad in our hearts by the Holy Ghost which is given unto us."
But there are many operations of the Holy Spirit, which the same apostle commemorates in a certain passage at such length as he thinks sufficient, and then concludes: "But all these works that one and the selfsame Spirit, dividing to every man severally as He will." Since, then, the sacrament is one thing, which even Simon Magus could have; and the operation of the Spirit is another thing, which is even often found in wicked men, as Saul had the gift of prophecy; and that operation of the same Spirit is a third thing, which only the good can have, as "the end of the commandment is charity out of a pure heart, and of a good conscience, and of faith unfeigned:" whatever, therefore, may be received by heretics and schismatics, the charity which covers the multitude of sins is the special gift of Catholic unity and peace; nor is it found in all that are within that bond, since not all that are within it are of it, as we shall see in the proper place.
At any rate, outside the bond that love cannot exist, without which all the other requisites, even if they can be recognized and approved, cannot profit or release from sin. But the laying on of hands in reconciliation to the Church is not, like baptism, incapable of repetition; for what is it more than a prayer offered over a man?
Source: On Baptism, Against the Donatists (New Advent)