If we have the light we shall be light. That is but putting in a picturesque form the very central truth of Christianity. The last word of the gospel is transformation. We become like Him if we live near Him, and the end for which the Master became like unto us in His incarnation and passion was that we might become like to Him by the reception of His very own life unto our souls. Light makes many a surface on which it falls flash, but in the optics of earth it is the rays which are not absorbed that are reflected; but in this loftier region the illumination is not superficial but inward, and it is the light which is swallowed up within us that then comes forth from us. Christ will dwell in our hearts, and we shall be like some poor little diamond-shaped pane of glass in a cottage window which, when the sun smites it, is visible over miles of the plain. If that sun falls upon us, its image will be mirrored in our hearts and flashing in our lives. The clouds that lie over the sunset, though in themselves they be but poor, grey, and moist vapour, when smitten by its beneficent radiance, become not unworthy ministers and attendants upon its glory. So, my brethren, it may be with us, for Christ comes to be our light, Because He is in us and with us we are changed into His likeness, and the names that are most appropriate to Him He shares with us. Is He the 'Son'?--we are sons. Is He 'the Light of the world'? His own lips tell us, 'Ye are the light of the world.' Is He the Christ? The Psalm says: 'Touch not my Christs, and do My prophets no harm.' Critics have quarrelled over these last chapters of the Book of Isaiah, as to whom the servant of the Lord is; whether he is the personal or collective Israel, whether he is Christ or His Church. Let us take the lesson that He and we are so united that His office that made the union possible, wherein He was sacrificed on the Cross for us all--belongs by derivation to His servants, and that He, the Sun of Righteousness, moves in the heavens circled by many another sun.
So, dear friends, these two convictions of these two facts, the dark earth, the sunlit, sunlike church, lie at the basis of all our missionary work. If once we begin to doubt about them, if once we begin to think that men have got a good deal of light already, and can do very well without much more, or if we at all are hesitant about our possession of the light, and the certitudes and the joys that are in it, then good-bye to our missionary zeal. We shall soon begin to ask the question, 'To what purpose is this waste?'--though the lips that first asked it, by the bye, did not much recommend it--and shall consider that money and resources and precious lives are too precious to be thrown away thus. But if we rightly appreciate the force of these twin principles, then we shall be ready to listen to the ringing summons.
II. We have here, in the second place, based upon these two facts, the summons to the Church. 'Shine, for thy light is come.' If we _have_ light, we _are_ light. If we are light, we shall shine; but the shining is not altogether spontaneous and effortless. Stars do not need to be bidden to shine nor candles either; but _we_ need the exhortation, because there are many things that dim the brilliance of our light and interfere with its streaming forth. True, the property of light is to shine, but we can rob the inward light of its beams. The silent witness of a Christian life transformed into the likeness of Jesus Christ is, perhaps, the best contribution that any of us can make to the spread of His kingdom. It is with us as it is with the great lights in the heavens. 'There is no speech nor language; their voice is not heart,' yet, 'their line has gone through all the earth, and their words to the end of the world.' So we may quietly ray out the light in us and witness the transforming power of our Master by the transparent purity of our lives. But the command suggests likewise effort, and that effort must be in the direction of the specific vocal proclamation of His name.