19 And this is the condemnation, that light is come into the world, and men loved darkness rather than light, because their deeds were evil.
[AD 382] Apollinaris of Laodicea on John 3:19
Those who love darkness instead of the light have no excuse. They did not fail to believe Christ because of their ignorance but because they wanted to do what is evil, which Christ’s teaching would not permit. Then, whenever we hear “they could not believe,” let us understand this as not referring to the ability of their nature or to their subjugation to someone else but to their own free reason, which enslaved them to dishonorable passions, not wanting to let them revolt from their very base habits. For these know “the light,” but do not come to it, in case they might be convicted for their hypocrisy for saying that they know God while denying him by their actions.

[AD 407] John Chrysostom on John 3:19
(Hom. xxviii. 2) As if He said, So far from their having sought for it, or laboured to find it light itself hath come to them, and they have refused to admit it; Men loved darkness rather than light. Thus He leaves them no excuse. He came to rescue them from darkness, and bring them to light; who can pity him who does not choose to approach the light when it comes unto him?

[AD 407] John Chrysostom on John 3:19
What He saith, 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," saith He, "to punish and to exact account of their deeds, they might have been able to say, 'this is why we started away from thee,' but now I am 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 hath brought in another place, where He saith, "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 sitteth in darkness, may perchance receive pardon; but one who after it is 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.

[AD 407] John Chrysostom on John 3:19
And observe how in another way He deprives them of all excuse, when He saith that, "the light came into the world." "Did they seek it themselves," He saith, "did they toil, did they labor to find it? The light itself came to them, and not even so would they hasten to it."

[AD 430] Augustine of Hippo on John 3:19-21
But if God hath discovered all men's works to be evil, how is it that any have done the truth, and come to the light, i. e. to Christ? Now what He saith is, that they loved darkness rather than light; He lays the stress upon that. Many have loved their sins, many have confessed them. God accuseth thy sins; if thou accuse them too, thou art joined to God. Thou must hate thine own work, and love the work of God in thee. The beginning of good works, is the confession of evil works, and then thou doest the truth: not soothing, not flattering thyself. And thou art come to the light, because this very sin in thee, which displeaseth thee, would not displease thee, did not God shine upon thee, and His truth show it unto thee. And let those even who have sinned only by word or thought, or who have only exceeded in things allowable, do the truth, by making confession, and come to the light by performing good works. For little sins, if suffered to accumulate, become mortal. Little drops swell the river: little grains of sand become an heap, which presses and weighs down. The sea coming in by little and little, unless it be pumped out, sinks the vessel. And what is to pump out, but by good works, mourning, fasting, giving and forgiving, to provide against our sins overwhelming us?

[AD 430] Augustine of Hippo on John 3:19
"And this is the judgment, that light is come into the world, and men loved darkness rather than light, because their deeds were evil." My brethren, whose works does the Lord find to be good? The works of none: He finds the works of all evil. How is it, then, that some have done the truth, and are come to the light? Whose works, in fact, are good? Hast Thou not come to justify the ungodly? "But they loved," saith He, "darkness rather than light." There He laid the emphasis: for many loved their sins; many confessed their sins; and he who confesses his sins, and accuses them, doth now work with God. God accuses thy sins: and if thou also accusest, thou art united to God. There are, as it were, two things, man and sinner. That thou art called man, is God's doing; that thou art called sinner, is man's own doing. Blot out what thou hast done, that God may save what He has done. It behoves thee to hate thine own work in thee, and to love the work of God in thee. And when thy own deeds will begin to displease thee, from that time thy good works begin, as thou findest fault with thy evil works. The confession of evil works is the beginning of good works.

[AD 444] Cyril of Alexandria on John 3:19
He lets not the condemnation of the unbelievers remain without consideration, but recounts its causes, and shows clearly that, according to the words of the Proverbs, Not unjustly is the net spread for the birds. For they, saith He, who when it was in their power to be illuminated preferred to remain in darkness, how will not they fairly be determiners of punishment against themselves, and self-invited to suffering which it was in their power to escape, if they had been right provers of things, choosing rather to be enlightened than not, and studying to make the baser things second to the better? But He preserved the mind of man free from the bonds of necessity, and tending by its own impulses to both sides, that it might justly receive praise for good things, and punishment for the contrary. As indeed He showeth in another place, saying, If ye be willing and obedient, ye shall, eat the good of the land; but if ye refuse and rebel, ye shall be devoured with the sword.

[AD 444] Cyril of Alexandria on John 3:19
Jesus says that unbelievers had the opportunity to be illuminated but preferred to remain in darkness. Such people, in fact, by failing to choose enlightenment, determine their own punishment against themselves and provoke their own suffering, which was in their power to escape. God preserved human freedom so that people might justly receive praise for good things and punishment for the contrary. As indeed he shows in another place, saying, “If you are willing and obedient, you shall eat the good of the land. But if you refuse and rebel, you shall be devoured by the sword.”

[AD 532] Pseudo-Dionysius the Areopagite on John 3:19
But his decision was, that the one is to be chosen, and the other avoided. To like effect is the saying, "Men loved darkness rather than light."
[AD 735] Bede on John 3:19-21
(in loc. c. 1) He calls Himself the light, whereof the Evangelist speaks, That was the true light; whereas sin He calls darkness.

Morally too they love darkness rather than light, who when their preachers tell them their duty, assail them with calumny.
But he that doeth truth cometh to the light, that his deeds may be made manifest, that they are wrought in God.

[AD 804] Alcuin of York on John 3:19
Here is the reason why men believed not, and why they are justly condemned; This is the condemnation, that light is come into the world.