God is Light. There is no darkness in him. He is "the Light that lights every man that comes into the world." (Saint John 1:9)
God provides spiritual light to all mankind in various degrees of intensity just like a house may be lit up by 25 watt, 50 watt, 75 watt, and a 100 watt bulbs interiorly while a sensory device turns on 1500 watt security lights outside.
A new believer might be represented by a 25 watt bulb lighting a closet of a house, while John the Baptist who was referred to as "a burning and shining light" by the Lord might be represented by the outdoor security light of 1500 watts.
God Almighty is "the Light of the world." He provides spiritual light for every man to know he exists, and light for believers to grow in sanctification. It is by God's Light in us we come to know him who is Light.
The Lord's anointed Saints walk in "the Light of the Lord" (Isaiah 2:5) and know the Lord better when they are one with Him.
King David who shined like an angel in his generation said, "The Lord is my Light." (Psalm 27:1) We know the Lord according to His Light in us.
"God wears Light as a garment." (Psalm 104:2)
Saul had no difficulty in recognizing it was God visiting him in the person of Christ shining brighter than the sun on the Damascus Road. When Jesus spoke majestically out of the blinding Light telling Saul it was He whom the Pharisee was persecuting, Saul encountered the greatest theological argument in the universe.
He previously presumed Jesus was an apostate, but now was convinced Jesus is God.
Great is the mystery of godliness.
"THE SUN SHALL BE NO MORE YOUR LIGHT BY DAY; NEITHER FOR BRIGHTNESS SHALL THE MOON GIVE LIGHT UNTO YOU: BUT THE LORD SHALL BE UNTO YOU AN EVERLASTING LIGHT, AND YOUR GOD YOUR GLORY." (Isaiah 60:19)
"THE LORD MY GOD WILL ENLIGHTEN MY DARKNESS."
( Psalm 18:28) And by His Light I will know Him.