Nicene and Post-Nicene Fathers, Vol. IV:
Writings in Connection with the Donatist Controversy.: Chapter 52

Chapter 52.—100.  Of all these several classes, then, no one doubts respecting those first, who are in the house of God in such a sense as themselves to be the house of God, whether they be already spiritual, or as yet only babes nurtured with milk, but still making progress with earnestness of heart, towards that which is spiritual, that such men both have baptism so as to be of profit to themselves, and transmit it to those who follow their example so as to benefit them; but that in its transmission to those who are false, whom the Holy Spirit shuns, though they themselves, so far as lies with them, confer it so as to be of profit, yet the others receive it in vain, since they do not imitate those from whom they receive it.  But they who are in the great house after the fashion of vessels to dishonor, both have baptism without profit to themselves, and transmit it without profit to those who follow their example:  those, however, receive it with profit, who are united in heart and character, not to their ministers, but to the holy house of God.  But those who are more thoroughly separated, so as to be rather out of the house than in the house, have baptism without any profit to themselves; and, moreover, there is no profit to those who receive it from them, unless they be compelled by urgent necessity to receive it, and their heart in receiving it does not depart from the bond of unity:  yet nevertheless they possess it, though the possession be of no avail; and it is received from them, even when it is of no profit to those who so receive it, though, in order that it may become of use, they must depart from their heresy or schism, and cleave to that house of God.  And this ought to be done, not only by heretics and schismatics, but also by those who are in the house through communion in the sacraments, yet so as to be outside the house through the perversity of their character.  For so the sacrament begins to be of profit even to themselves, which previously was of no avail.