For every one that doeth evil hateth the light. — In this and the next verse we have the explanation of the choice of the darkness and rejection of the light. The fact itself is first stated more strongly. Not only does the man that doeth evil love darkness rather than light, but he hates the light. (Comp. Note on John 7:7.) Its presence makes manifest and reproves his works, which he would hide even from himself. It illumines the dark and secret chambers of the heart, and reveals thoughts and deeds which conscience, seeing in this light, trembles at, and turns away to darkness that it may hide itself from its own gaze.
It has been often noted that the word “doeth,” in this and the following verse, represent different words in the original. Perhaps we may distinguish them in English by rendering this verse: “Every one that practiseth evil.” It is not less important to note that the word for evil here differs from the word so rendered’ in the last clause of the previous verse. Strictly, and the change of word seems to demand a strict interpretation (comp. Note on John 5:29), it is not that which is positively, but that which is negatively, evil — that which is trivial, poor, worthless. The man who practiseth such things misses the aim of life, and turns from the light that would point it out to him. He does many things, but forgets that one thing is needful, and spends a life-time in trifles without any permanent result. We are familiar with the thought that immorality shuns the light and warps the will, and thus darkens knowledge and weakens faith; but we remember too seldom the deadening effect of an unreal and aimless existence which is not truly a life.
Should be reproved. — The margin will show that our translators felt a difficulty about this word (see Notes on Matthew 18:15), where it is rendered “tell him his fault,” and comp. the other instances in this Gospel, John 8:9; John 8:46 (“convince” in both), and especially John 16:8 (“reprove,” and margin “convince”). The moral idea is exactly illustrated by the action of light, which makes manifest the wrong, and leads the conscience to see it and repent of it. It is through this chastening that the man passes from darkness to light. It is because men shrink from this chastening that they hate the light. (Comp. Notes on the remarkable parallel in Ephesians 5:11 et seq.)