World Wide Study Bible
a Bible passage
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.