The apostle John, designated as "the other disciple, whom Jesus loved" (John 20:2), used the concept of agape love more than any other New Testament writer, even teaching that "God is love" (1 John 4:8). Likewise, John tells us that "God is light, and in him is no darkness at all" (1 John 1:5), and he uses the concept of light (phos) more than any other writer.
In just the same way he uses the primary word for life (zoe) more than any other writer and discusses "That which was from the beginning, which we have heard, which we have seen with our eyes, which we have looked upon, and our hands have handled, of the Word of life" (1 John 1:1), identifying Christ as life and the Fountain of life.
Christ, of course, has existed "from the beginning" and is the Creator of physical life on earth (Colossians 1:16; Acts 17:28). But in a special way, He is "the life" (John 14:6), and, as we see in our text, "in Him was life," denoting salvation and eternal life based on His own atonement for sin.
Concerning light, Christ not only created physical light (Genesis 1:3) and later light sources (Genesis 1:14), but He is light, referring to revelation of the things of God to men, for His "life was the light of men."
But most of all, "God is love." The first time John mentions agape love, we are told that "God so loved the world," and that His free and undeserved love drove Him to give "his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life" (John 3:16). "Herein is love . . . that he loved us, and sent his Son to be the propitiation for our sins" (1 John 4:10). JDM