Jesus said to him, ‘I am the way, and the truth, and the life. No one comes to the Father except through me. If you know me, you will know my Father also. From now on you do know Him and have seen Him.’
Philip said to him, ‘Lord, show us the Father, and we will be satisfied.’
Jesus said to him, ‘Have I been with you all this time, Philip, and you still do not know me? Whoever has seen me has seen the Father. How can you say, “Show us the Father”? Do you not believe that I am in the Father and the Father is in me? The words that I say to you I do not speak on my own; but the Father who dwells in me does His works. Believe me that I am in the Father and the Father is in me; but if you do not, then believe me because of the works themselves. Very truly, I tell you, the one who believes in me will also do the works that I do and, in fact, will do greater works than these, because I am going to the Father. I will do whatever you ask in my name, so that the Father may be glorified in the Son. If in my name you ask me for anything, I will do it.
This is perhaps a little bit confusing at first, and we probably read the passage and move on to something else. The message we get, at first sight, is that Jesus says He is at one with the Father; God.
But let's analyse what He says a bit more.
Here Jesus is saying something that the disciples do not understand. They think He is saying that He is the Son of God, He is at one with God. But what He is in fact saying is "I am God. I am God, personified. I am God in the shape of a human."
Jesus often taught people to refer to God as the Father. And He often said that He is the Son of God. This must have scandalised the Jews and their elders, the Pharisees and Sadducees, who crucified Him for the blasphemy of saying He is the Son of God.
Can you imagine their reaction had He said outright, "I am God!"
This is the closest He comes to saying just that. And His disciples still did not understand.
"Whoever has seen me has seen the Father," meaning "I am God personified."
He goes on to say, "I am in the Father and the Father is in me," again, explaining that they are one, He is God in human form.
He repeats this message and explains that the works He has done (miracles) are done through God Who lives in Him.
From olden times, as far back as Abraham, Moses and the prophets, the Jews believed in God. One God. One living God.
Other people had many deities like the Romans and the Greeks for instance.
The Jews had one living God. The God of Abraham and Moses Who spoke through the prophets.
Then Jesus came on the scene. He said He was the Son of God; and in time, many Jews accepted this. In their minds there was a living God in Heaven, and this Jesus, His only Son. Albeit, right now in this passage, He is telling them He is God, (i.e. part of the Trinity), but they don't see it or understand it.
After His death and resurrection, the early Christians came to associate God and Jesus together. In their minds, and central to their faith, there was a living God, and this man Jesus who died and was raised from the dead was (is) His only Son.
When Jesus ascended to Heaven, as promised, He sent down His Holy Spirit, (the Spirit of God), to dwell within the disciples and to open their eyes and minds and to understand. That is how, at Pentecost, they were able to finally understand and preach the Word of God to all nations.
To understand that the three, God, Jesus, and the Holy Spirit, are indeed one.
God - an invisible living Being, Creator of all and everything, somewhere in Heaven. Omnipotent. Caring and loving.
Jesus - God personified. Appearing on earth as a human being. The only Son of God. Our means of salvation and forgiveness.
The Holy Spirit - The Spirit (soul) of God. Descending upon the disciples, and upon us if we ask Him, to enlighten us, to help us, and to guide us back home to the Father, God.