Gospel of John refers Jesus to his unity with the Father. How would you express Jesus's relationship with God?
This is a great question. The Gospel of John is a great book that speaks of the person and work of Jesus. The most important chapters when it comes to the relationship between Jesus and his father are John 1 and 17.
In John 1, the author of John states:
"In the beginning was the word, and the word was with God and was God."
This verse shows that author of John viewed Jesus as God. This is one of the reasons why the church believes in the trinity.
In John 17, Jesus prays to his father and in this prayer communicates two important points. First, he asks to be glorified with the glory that he had with the father. The implication is that Jesus shared the same glory with he father before his mission to save people. This shows that the relationship with his father was one of equality.
Second, Jesus states that he has completed his mission of speaking the truth and reaching his people. This shows that in a sense that the son (Jesus) was subordinate to the father from a functional point of view.
In short, according to John, Jesus and the father are one (John 10:31), but they have different roles.