“And God said, Let there be light: and there was light. And God saw the light, that it was good: and God divided the light from the darkness. And God called the light Day, and the darkness he called Night. And the evening and the morning were the first day,” (Genesis 1:3-5, KJV).
“And God said, Let there be lights in the firmament of the heaven to divide the day from the night; and let them be for signs, and for seasons, and for days, and years,” (Genesis 1:14, KJV).
“And let them be for lights in the firmament of the heaven to give light upon the earth: and it was so,” (Genesis 1:15, KJV).
“Then spake Jesus again unto them, saying, I am the light of the world: he that followeth me shall not walk in darkness, but shall have the light of life,” (John 8:12, KJV).
“Ye are the light of the world. A city that is set on an hill cannot be hid,” (Matthew 5:14, KJV)
“In whom the god of this world hath blinded the minds of them which believe not, lest the light of the glorious gospel of Christ, who is the image of God, should shine unto them….For God, who commanded the light to shine out of darkness, hath shined in our hearts, to give the light of the knowledge of the glory of God in the face of Jesus Christ,” (II Corinthians 4:4,6, KJV).
“For such are false apostles, deceitful workers, transforming themselves into the apostles of Christ. … And no marvel; for Satan himself is transformed into an angel of light,” (II Corinthians 11:13-14, KJV).
These verses teach some wonderful truths about Jesus, the gospel, salvation, conversion, the role of God’s people, the work of Satan, unbelievers, and many more. A few examples:
Salvation is by Fiat (by the simple Word of God).
A false gospel resembles the true gospel in some way.
Christians, by their new nature, reflect the Light of Jesus. (They have no light of their own)
Many other verses that use the metaphor could be shown. But they all have something in common. It is the interpretation principal of “first use”. They all hearken back to Genesis 1. Deny God’s creation of light and darkness by Fiat, and all other uses are brought into question. Don’t tell me one’s understanding of Genesis doesn’t matter. It matters.