John Calvin on John 12:46

46. I am come into the worm as a light. In order to render his disciples more bold and persevering, he proceeds still farther in maintaining the certainty of faith. And, first, he testifies that he came into the world to be a light, by which men might be delivered from darkness and errors; and, at the same time, he points out the means of obtaining so great a benefit, when he says, that whosoever believeth in me may not remain in darkness. Besides, he accuses of ingratitude all who, after having been taught by the Gospel, do not separate themselves from unbelievers; for the higher the excellence of this benefit, of being called from darkness to light, the less excusable are they who, through their indolence or carelessness, quench the light that had been kindled in them.

The words, I am come into the world as a light, are highly emphatic; for though Christ was a light from the beginning, yet there is a good reason why he adorns himself with this title, that he has come to perform the part of a light. That we may perceive distinctly the various steps, he shows, first, that he is a light to others rather than to himself; secondly, that he is a light, not only to angels, but also to men; thirdly, that he was manifested in the flesh, in order that he might shine with full brightness.

The term, whosoever, appears to have been added on purpose, partly, that all believers, without exception, may enjoy this benefit ill common, and partly, to show that the reason why unbelievers perish in darkness is, that, of their own accord, they forsake the light. Now, if the whole wisdom of the world were collected into one mass, not a single ray of the true light would be found in that vast heap; but, contrary, it will be a confused chaos; for it belongs to Christ alone to deliver us from darkness.

John 12:47-50

47. And if any man hear my words, and do not believe them, “Et ne les croit point.” I do not judge him; for I came not to judge the world, but to save the world. 48. He who rejecteth me, and receiveth not my words, hath one who judgeth him. The word which I have spoken shall judge him at the last day. 49. For I have not spoken from myself; but the Father who hath sent me hath given me a commandment what to say and what to speak. 50. And I know that his commandment is eternal life: those things, therefore, which I speak, I speak as my Father hath told me.