59 Another Secundinus of Carpis said: "Are heretics Christians or not? If they are Christians, why are they not in the Church of God? If they are not Christians, let them be made so. Else what will be the reference in the discourse of the Lord, in which He says, 'He that is not with me is against me; and he that gathers not with me scatters abroad?' Whence it is clear that on strange children and the offspring of Antichrist the Holy Spirit cannot descend by the laying on of hands alone, since it is clear that heretics have not baptism."
60. To this we answer: Are the unrighteous Christians or not? If they are Christians, why are they not on that rock on which the Church is built? For they hear the words of Christ and do them not. If they are not Christians, let them be made so. Else what will be the reference in the discourse of our Lord, in which He says, "He that is not with me is against me; and he that gathers not with me scatters abroad?" For they scatter His sheep who lead them to the ruin of their lives by a false imitation of the Lord. Whence it is clear that upon strange children (as all the unrighteous are called), and upon the offspring of Antichrist (which all are who oppose themselves to Christ), the Holy Spirit cannot descend by the laying on of hands alone, if there be not added a true conversion of the heart; since it is clear that the unrighteous, so long as they are unrighteous, may indeed have baptism, but cannot have the salvation of which baptism is the sacrament. For let us see whether heretics are described in that psalm where the following words are used of strange children: "Deliver me, O Lord, from the hand of strange children, whose mouth speaks vanity, and their right hand is a right hand of falsehood: whose sons are like young shoots well established, and their daughters polished after the similitude of the temple. Their garners are full, affording all manner of store; their sheep are fruitful, bringing forth plenteously in their streets; their oxen are strong: there is no breaking down of their fence, no opening of a passage out, no complaining in their streets. Men deemed happy the people that is in such a case; rather blessed is the people whose God is the Lord." If, therefore, those are strange children who place their happiness in temporal things, and in the abundance of earthly prosperity, and despise the commandments of the Lord, let us see whether these are not the very same of whom Cyprian so speaks, transforming them also into himself, that he may show that he is speaking of men with whom he held communion in the sacraments: "In not keeping," he says, "the way of the Lord, nor observing the heavenly commandments given us for our salvation. Our Lord did the will of His Father, and we do not do the will of the Lord, being eager about our patrimony or our gains, following after pride, and so forth." But if these could both have and transmit baptism, why is it denied that it may exist among strange children, whom he yet exhorts, that, by keeping the heavenly commandments conveyed to them through the only-begotten Son, they should deserve to be His brethren and the sons of God?
Source: On Baptism, Against the Donatists (New Advent)