In this longer version of the Last Supper, Lord Jesus is giving his last teachings to his beloved apostles, but they were concern about Jesus’s coming disappearance (John 13:31-37), as the Lord foretold them.
But Lord Jesus reassured them that He was going to prepare a place for them, that in God’s presence, there was place for many more, not only Him, and that for sure, He will return to take them with Him (John 14:3), and He told them that they ‘new the way’ to God’s Kingdom (John 14:4).
Lord Jesus declared openly to the present there, that He Himself was ‘the Way, the Truth and the Life.’
He is the way, because He made possible through his incarnation and atoning sacrifice, the forgiveness of sin and justification before God from our fallen nature. He also declared that He was the ‘only way’ (John 14:6), but clearly declaring that there was not other way to God than through Him alone.
He is the Truth, because He is the only all-knowing, omniscient God (John 14:7) that can show the world all truth about anything, specially the truth about the invisible spirit world, and the true way of righteousness. Anything else apart from Him, it is only partial truth, or not truth at all.
He is the Life, because He Himself won the right to forgiveness and eternal life for all those who submitted to Him. He did not show ‘the way’ to life. He Himself was ‘the Life’.
The Apostles knew the way, because they knew Him, who declared to be “the only way to God”, implying that nobody or anything else could achieve that goal. No Buddha, no Mohammed, not Zarathustra or any other ‘enlighten’ could gain access to God without Christ. Indirectly, by calling Himself ‘The Truth’ in singular, He implied all other religions and religions leaders as false. That is why Christianity is an exclusivist religion. Without Jesus there is no salvation.
After this, Apostle Phillip asked the Lord to show them the Father. Meaning to show them YHWH, the God of Israel.
Jesus replied with surprise that how come He had been in their midst and they had not recognized Him (John 14:8-9).
Lord Jesus proceeds here to give a theological speech about the nature of the Divinity, what we call Trinity, Elohim - אֱלֹהִ֑ים , that is ONE SINGLE GOD AND ENTITY, manifested in three different distinct beings, known as FATHER, WORD, and SPIRIT, even through He does not deal here with the Holy Spirit directly.
In plain and clear language, Lord Jesus of Nazareth, tells them that the Father lives within Himself, and He Himself also lives inside the Father (John 14:10-11). This leaves aside the teachings of those who deny the divinity of Jesus by saying that the Father ‘lives in Jesus’ the same way He lives spiritually in all believers, because Jesus also says that HE lives within the Father, thing that no creature can do, except Jesus, who with this He makes Himself equal in power and dignity to YHWH, able to do the same things He does.
Lord Jesus also speaks that whoever has seen Him and know Him, not only has known YHWH, but has also seen the invisible God of Israel (John 14:7). Even though this could be considered a blasphemy in the mouth of any created being, it makes Jesus equal to YHWH in Glory and nature. But however, this does not mean that He is YHWH as a person, since He many times prayed to YHWH (Luke 22:42) as a different being, and YHWH Himself spoke to Him from Heaven (Luke 3:22). This also leaves aside the modalism that teaches that God manifests Himself sometimes as Father, sometimes as Son and sometimes as Spirit, each at the time. The Father, Son and Spirit of the Bible are three different entities, independent from each other and each have their own will (Luke 22:42; Matthew 24:36; 26:39), even though by a common divine nature they all concord.
But after having said this, Lord Jesus declared his eternal subjection to the Father, as Son (John 14:10), not because He belonged to a lesser nature than his Father, but because of a voluntary subjection to Him within the order of the Trinity.
Closing the teaching on his divinity, Lord Jesus said that whatever we ask HIM in his own Name, He will do it (John 14:13-14), that allowing prayers to be address to Him, putting Himself in the place of God.