12 Lucianus of Rucuma said: "It is written, 'And God saw the light that it was good, and God divided the light from the darkness.' If light and darkness can agree, then can there be something in common between us and heretics. Therefore I give my judgment that heretics should be baptized."
13. To him the answer is: If light and darkness can agree, then can there be something common between the righteous and unrighteous. Let him therefore declare his judgment that those unrighteous should be baptized afresh whom Cyprian confuted within the Church itself; or let him who can say if those are not unrighteous "who renounce the world in words and not in deeds."
Source: On Baptism, Against the Donatists (New Advent)