Finally, they think that the question of baptism is hidden, with which they deceive wretched souls. But while they say that none have baptism who were baptized outside the communion of the one Church, they received with undiminished honors the followers of Maximianus, with those whom they baptized in schism outside the Donatist communion, and this at least they cannot hide.
30. "But these things," they say, "bring no pollution in the cause of peace; and it is well to bend to mercy the rigor of extreme severity, that broken branches may be grafted in anew." Accordingly, in this way the whole question is settled, by defeat in them, by the impossibility of defeat for us; for if the name of peace be assumed for even the faintest shadow of defense to justify the bearing with wicked men in schism, then beyond all doubt the violation of true peace itself involves detestable guilt, with nothing to be said in its defence throughout the unity of the world.
Source: Answer to Letters of Petilian, Bishop of Cirta (New Advent)