". . .and truly our fellowship is with the Father, and with his Son Jesus Christ." (1 John 1:3)
Jesus prayed (John 17) that we, His chosen disciples, might have the same kind of relationship with the Heavenly Father that Jesus Himself had throughout eternity. Our minds may not totally grasp that wonder down here—except as we try to understand something of the key of walking "in the light" (1 John 1:7).
The nature of light in our universe gives us clues:
Light is unchangeable; one cannot make light dark.
Light exposes everything (reveals and brings clarity).
Light is the sustainer of all life as we know it.
The nature of darkness is also very instructive:
Darkness is driven away by the smallest spark.
Darkness covers everything (hides and obscures).
Darkness will kill all life as we know it.
"The path of the just is as the shining light. . . . The way of the wicked is as darkness" (Proverbs 4:18-19). The promise of fellowship with God is that He "will lead them in paths that they have not known" and that He "will make darkness light before them, and crooked things straight" (Isaiah 42:16).
Therefore, "let us, who are of the day, be sober, putting on the breastplate of faith and love; and for an helmet, the hope of salvation" (1 Thessalonians 5:8). Since we were "sometimes darkness" (Ephesians 5:8) but have been delivered from "the power of darkness" (Colossians 1:13), we should no longer "fellowship with the unfruitful works of darkness, but rather reprove them" (Ephesians 5:11). HMM III