In all languages, light is the natural symbol for three things: knowledge, joy, purity. The one ray is broken into its three constituent parts. But just as there are some surfaces which are sensitive to the violet rays, say, of the spectrum, and not to the others, so John's intense moral earnestness makes him mainly sensitive to the symbolism which makes light the expression, not so much of knowledge or of joy, as of moral purity. And although that is not exclusively his use of the emblem, it is predominately so, and it is so here. To walk in the light' then; is, speaking generally, to have purity, righteousness, goodness, as the very element and atmosphere in which our progressive and changeful life is carried on.
Note, too, before I go further, that very significant antithesis: we walk'; He is--God is in the light essentially, changelessly, undisturbedly, eternally; and the light in which He is, His own calm home, His habitation from eternity,' is light which has flowed out from Himself as a halo round the midnight moon. It is all one in substance to say God is in light, or, as the Psalmist has it, He covered Himself with light as with a garment,' and to say, God is light.'
But, side by side with that changeless abiding in the perfect purity, which is inaccessible, the Apostle ventures to put, not in contrast only, but in parallel (as He is), our changing, effortful, active, progressive life in the light (God is); we walk.
So, then, the essential of a Christian character is that the light of purity and moral goodness shall be as the very orb, in the midst of which it stands and advances. That implies effort, and it implies activity, and it implies progress. And we are only Christians in the measure in which the conscious activities of our daily lives, and the deepest energies of our inward being, are bathed and saturated with this love of, and effort after, righteousness. It is vain, says John, to talk about fellowship with God, unless the fellowship is rooted in sympathy with Him in that which is the very heart of His Being, the perfect light of perfect holiness. Test your Christianity by that.
Then, still further, there is implied in this great requirement of walking in the light, not only activity and effort, and progress in purity, but also that the whole of the life shall be brought into relation with, and shall be moulded after, the pattern of the God in whom we pro-less to believe. Religion, in its deepest meaning, is the aspiration after likeness to the god. You see it in heathenism. Men make their gods after their own image, and then the god makes the worshippers after his image. Mars is the god of the soldier, and Venus goddess of the profligate, and Apollo god of the musical and the wise, etc., and in Christianity the deepest thing in it is aspiration and effort after likeness to God. Love is imitation; admiration, especially when it is raised to the highest degree and becomes adoration, is imitation. And the man that lies before God, like a mirror in the sunshine, receives on the still surface of his soul--but not, like the mirror, on the surface only, but down into its deepest depths--the reflected image of Him on Whom he gazes. We all with unveiled face, mirroring glory, are changed into the same image.' So to walk in the light is only possible when we are drawn into it, and our feeble feet made fit to tread upon the radiant glory, by the thought that He is in the light. To imitate Him is to be righteous. So do not let us forget that a correct creed, and devout emotions, ay! and a morality which has no connection with Him, are all imperfect, and that the end of all our religion, our orthodox creed and our sweet emotions and inward feelings of acceptance and favour and fellowship, are meant to converge on, and to produce this--a life and a character which lives and moves and has its being in a great orb of light and purity.
But another thing is included in this grand metaphor of my text. Not only does it enjoin upon us effort and activity and progress in the light and the linking of all our purity with God, but also, it bids us shroud no part of our conduct or our character either from ourselves or from Him. Bring it all out into the light. And although with a penitent heart, and a face suffused with blushes, we have sometimes to say, See, Father, what I have done! it is far better that the revealing light should shine down upon us, and like the sunshine on wet linen, melt away the foulness which it touches, than that we should huddle the ugly thing up in a corner, to be one day revealed and transfixed by the flash of the light turned into lightning. He that doeth the truth cometh to the light, that his deeds may be made manifest.'