John particularly emphasizes the deity of Christ. When you watch the Gospel of John movie, the deity just screams in your face. In all 4 gospels, Christ is God, but it just is emphasized more in John.
John is the Gospel of the I AM's. I AM is a name of God as Exodus tells us.
I AM the bread of life.
I AM the way the truth, and the life.
I AM the good shepherd.
I AM the door.
I AM the bread of life.
I AM the light of the world.
I AM the resurrection and the life.
Before Abraham was born, I AM.
Except you believe that I AM, you shall die in your sins.
The arresters fall back and down when the Lord Jesus utters, I AM.
In Greek it is ego eimi. Since eimi by itself means I am, adding ego in front of it makes the I emphatic, like I and none other AM.
The ego eimi may be obscured by translations that add "he" after the am (I am he) where there is no word "he" in Greek.
John also has more material proportionately on Judea, as opposed to Galilee than the other 3 (the Synoptics.
The Gospel of John is the gospel of signs (miracles):
He turns water to wine, feeds 5000 (not counting women and children), makes the blind see, even raises the dead (including Himself from the dead). There are something like 8 great signs.
Purpose statement:
John 20:30-31
Many other signs therefore did Jesus in the presence of the disciples, which are not written in this book: but these are written, that you may believe that Jesus is the Christ, the Son of God; and that believing you may have life in his name.