First of all trying to form doctrines via only the KJV bible is not that easy due to the trinitarian mind-set of the interpreters. You will find verses such as 1 John 5:7 that will cause confusion when trying to understand the Godhead.
Phl 2:6-7 who, though he was in the form of God, did not count equality with God a thing to be grasped, but emptied himself, taking the form of a servant, being born in the likeness of men.
Remember, Jesus is the second Adam. The first Adam made himself as God whereas Jesus did not but instead He took on the form of a servant.
Jesus did fully and completly die on the cross but, as His Father promised, He did not leave Jesus in the grave to see corruption but raised Him and glorified Him at His right hand.
If you read the words of Jesus carefully you will find that the now Holy Spirit is Jesus, He is the comforter, Helper.
Jhn 14:16-18 "And I will pray the Father, and He will give you another Helper, that He may abide with you forever-- "the Spirit of truth, whom the world cannot receive, because it neither sees Him nor knows Him; but you know Him (Jesus), for He (Jesus) dwells with you and will be in you. "I (Jesus) will not leave you orphans; I (Jesus) will come to you.
Jesus was sent by the Father to teach us and to be our example. Jesus was helping the disciples in this but was now leaving them but He said there would be another helper He would not leave them as orphans, the glorified Christ is that helper.
This comforter, Holy Spirit was not yet because Jesus was not yet glorified. The KJV says, not yet given but the word (given) is not in the original langauge.
Jhn 7:39 and this he said of the Spirit, which those believing in him were about to receive; for not yet was the Holy Spirit, because Jesus was not yet glorified.
The Son at His glorification became the promised Holy Spirit.
Act 2:33 Now he (Jesus) sits on the throne of highest honor in heaven, at God's (YAHWEH's) right hand. And the Father, as he had promised, gave him the Holy Spirit to pour out upon us, just as you see and hear today.
So who is this Holy Spirit that is being poured out?
2Cr 3:8 How shall not the ministration of the Spirit be rather glorious?
2Cr 3:17 Now the Lord is that Spirit: and where the Spirit of the Lord [is], there [is] liberty.
The Father did leave Jesus on the cross and to Jesus this was more horrible then the beatings. A trinitarian cannot grasp this.
Mat 27:46 And about the ninth hour Jesus cried with a loud voice, saying, Eli, Eli, lama sabachthani? that is to say, My God, my God, why hast thou forsaken me?
Jesus' soul and body was in the grave or hell, His spirit/life/breath went to YAHWEH who gives it. This spirit/life/breath is the same life that was given to Adam at creation when Adam became a living soul and is the same life that we all have.
Psa 16:10 For thou wilt not leave my soul in hell; neither wilt thou suffer thine Holy One to see corruption (body).
Act 2:27 Because thou wilt not leave my soul in hell, neither wilt thou suffer thine Holy One to see corruption (body).
Act 2:31 He seeing this before spake of the resurrection of Christ, that his soul was not left in hell, neither his flesh did see corruption.