There is one main theme in this Gospel, thinking spiritually (1:1). Everything John writes is intended to reveal that behind all physical Creation is the grace, truth and love of God in Jesus. From the universe to our unique individuality, everything was spiritually designed by God to be spiritually understood and experienced. That's why I say the Gospel of John is like the Rosetta Stone. It opens the spiritual door to deeper understanding of the first three Gospels. They come alive and together with the rest of the New Testament and the Old Testament, we see life, love life and live life spiritually. John helps us to be His light living spiritual reality to the fullest.
In Christ Jesus life is unfolding in a new way every day; a light being turned on in someone's life. The fact that each person is born brand new and unique is a potential light in process and progress. The revelation that newness is a way of life for everyone is a light being turned on. Turned on to the fact that every next moment is not a subject of fear but of opportunity to see what God is going to do that's new. This is what makes spiritual life challenging and exciting. It's expecting something good will happen and that even the bad stuff can be turned into something truly positive. The spiritual promise in John's Gospel.