John 3:19
“And this is the condemnation, that light has come into the world, and men loved darkness rather than light.”
What He says, is of this kind: “they are punished, because they would not leave the darkness, and hasten to the light.” And hence He goes on to deprive them of all excuse for the future: “Had I come,” says He, “to punish and to exact account of their deeds, they might have been able to say, 'this is why we started away from you,' but now I have come to free them from darkness, and to bring them to the light; who then could pity one who will not come from darkness unto light? When they have no charge to bring against us, but have received ten thousand benefits, they start away from us.” And this charge He has brought in another place, where He says, “They hated Me without a cause”: and again, “If I had not come and spoken unto them, they had not had sin.” For he who in the absence of light sits in darkness, may perchance receive pardon; but one who after it has come abides by the darkness, produces against himself a certain proof of a perverse and contentious disposition. Next, because His assertion would seem incredible to most, (for none would prefer “darkness to light,”) He adds the cause of such a feeling in them. What is that?
Source: Homilies on the Gospel of John (New Advent)