In the beginning was the Word, and the Word was with God, and the Word was God. He was in the beginning with God. All things came into being through him, and without him not one thing came into being. What has come into being in him was life, and the life was the light of all people. The light shines in the darkness, and the darkness did not overcome it.
The Gospel of John is the most overtly metaphysical of the four Gospels; it's focus is not on the events of the life of Jesus of Nazareth so much as on the Christ—the infinite spiritual Power that Jesus came to embody and demonstrate. This is clear from the very first verses, which deliberately echo the beginning of the Book of Genesis and present a fresh understanding of the entire process of Creation. The Word—the light that shines in the darkness—is the Christ. It is the indwelling, immediate Presence and Power of God that is the true identity of every person. We're told at 1:17 that "the law was given through Moses." That doesn't mean that Moses was the law; he was the channel through which awareness of the law flowed into our collective human consciousness. Similarly, "grace and truth came through Jesus Christ." Jesus became fully the Christ in expression, as a shining example of the potential that lives in each and all of us. If you understand "Word" to be "the Christ," the truth of our spiritual Oneness with God, the passage becomes a ringing affirmation of our innate Oneness with all that God is.