32 Felix of Bagai said: "As when the blind leads the blind, both fall into the ditch, so when a heretic baptizes a heretic, both fall together into death."
33. This is true, but it does not follow that what he adds is true. "And therefore," he says, "the heretic must be baptized and brought to life, lest we who are alive should hold communion with the dead." Were they not dead who said, "Let us eat and drink, for tomorrow we die?" for they did not believe in the resurrection of the dead. Those then who were corrupted by their evil communications, and followed them, were not they likewise falling with them into the pit? And yet among them there were men to whom the apostle was writing as being already baptized; nor would they, therefore, if they were corrected, be baptized afresh. Does not the same apostle say, "To be carnally-minded is death?" and certainly the covetous, the deceivers, the robbers, in the midst of whom Cyprian himself was groaning, were carnally-minded. What then? Did the dead hurt him who was living in unity? Or who would say, that because such men had or gave the baptism of Christ, that it was therefore violated by their iniquities?
Source: On Baptism, Against the Donatists (New Advent)