“Again Jesus spoke to them, saying, ‘I am the light of the world. Whoever follows me will not walk in darkness, but will have the light of life.’” - Luke 2:10
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Christ is the true Light. The world was in darkness until He appeared. The light of reason could not guide man to God. The light of the law could not save man from sin. The light of prophecy pointed forward, but the substance was not yet come. When Christ came into the world, the day broke and the shadows fled. He is the Sun of righteousness, and all other lights derive their brightness from Him. In Him was life, and the life was the light of men. All who are enlightened unto salvation receive their light from Christ. He opens the eyes of the blind and turns them from darkness to light and from the power of Satan unto God.
This true Light shines in the darkness. The world lay in the wicked one, under error and ignorance, superstition and misery, but Christ appeared to dispel the darkness. He shined in the days of His flesh, and He continues to shine by His Word and Spirit. Though multitudes love darkness rather than light because their deeds are evil, yet the Light continues to shine. The unworthiness of men does not extinguish the glory of Christ. Many shut their eyes against the Light, but the Light is not therefore dimmed. The day will come when every eye shall see Him.
Christ is the Light of the world, not of the Jews only, but of the Gentiles also. The light that shines from Him is sufficient for all. No sinner is so lost that Christ cannot enlighten him. No heart is so dark that Christ cannot change it. Those who follow Him shall not walk in darkness. Christ does not merely show the way; He is the way. He does not merely teach the truth; He is the truth. He does not merely give life; He is life. Blessed are they who sit at His feet and rejoice in His light.
(Taken From Matthew Henry's Commentary on John)