In the account of the creation, we read that the first word from God was, "Let there be light" (Genesis 1:3). He did not actually create or make light, as He did everything else, since God is light (1 John 1:5). He did create darkness, however (Isaiah 45:7), and then divided the light from the darkness. "And God called the light Day, and the darkness he called Night" (Genesis 1:5).
Although the darkness of night can be a time of blessing through rest and sleep, it also soon came to symbolize spiritual darkness. Most evil deeds are done at night, and Christians are warned to "have no fellowship with the unfruitful works of darkness" (Ephesians 5:11). God has called us "out of darkness into his marvellous light" (1 Peter 2:9).
In that wonderful age to come, when we go to dwell in our eternal home in the Holy City, the city gates "shall not be shut at all by day: for there shall be no night there" (Revelation 21:25). "And the city had no need of the sun, neither of the moon, to shine in it: for the glory of God did lighten it, and the Lamb is the light thereof" (Revelation 21:23).
The sun and moon will still be functioning in the heavens, however, for "he hath also stablished them for ever and ever" (Psalm 148:6). In fact, all the stars will also shine for ever and ever" (Daniel 12:3). Our God is the Creator, not an un-creator. As wise Solomon noted: "I know that, whatsoever God doeth, it shall be for ever" (Ecclesiastes 3:14).
The sun and moon will still be there, but their light will not be needed in the Holy City where we shall live, for the Lamb of God will also be the Lamp of God. He is the Light of the world and where He is, in His eternal glory, there can be no night. HMM