Jesus is God manifest in the flesh, fully God, and fully man.
According to His deity He does not have a beginning, which He is from everlasting.
According to His humanity He has a beginning, which He is the beginning of creation, and the firstborn among the creatures, which God calls things that have not happened yet, as thought they already happened, for if it is a plan of God to happen in the future it is the same as if it happened in the beginning, for it will surely come to pass with no hindrance, which the Lamb was slain from the foundation of the world, and all the works were finished from the foundation of the world.
So although the man Christ Jesus was not born until 4000 years after the start of creation He is still considered to be in the beginning.
Which the Word of God is the plan of God to come in the future in flesh, and that plan was with Him before He started creation, and without that plan God would of not created anything that He created, for Jesus is the reason creation is successful, eternal life, and to judge the angels and people.
Many people cannot accept Jesus is God for they say God is bigger than a human image, and they do not accept Him as a being other than that image.
But when the Bible says God was manifest in the flesh it means that God manifest all His attributes to the man Christ Jesus, which He is the fulness of the Godhead bodily, and He has the Spirit without measure, and it pleased the Father that in Him all fulness should dwell.
And the man Christ Jesus the personal human body of God, which He laid down His life for us, and purchased the Church with His own blood.
And the Spirit in Christ is still connected to the omnipresent Spirit of God for He cannot be separated.
Jesus does not have His own personal Spirit that moves around with Him for there cannot be a double portion of the Spirit in one place, and an empty space where the Spirit is not at.
But Jesus moves through the Spirit and wherever He is at the Spirit is there.
Which makes it easier to understand how Jesus can be God, but be God in a visible image, for the Spirit cannot be separated so Jesus is an omnipresent Spirit that showed us a visible image of Himself.
1Ti 6:14 That thou keep this commandment without spot, unrebukeable, until the appearing of our Lord Jesus Christ:
1Ti 6:15 Which in his times he shall shew, who is the blessed and only Potentate, the King of kings, and Lord of lords;
1Ti 6:16 Who only hath immortality, dwelling in the light which no man can approach unto; whom no man hath seen, nor can see: to whom be honour and power everlasting. Amen.
No person will ever see Jesus according to Him being God as an invisible Spirit, but we can see a visible image of Jesus, which the throne in heaven is the throne of God and the Lamb, God in the glorified body of the man Christ Jesus.
Which the man Christ Jesus prayed to the Father that the saints could have the same glory that He had in the beginning, which He was not talking about glory as God for the saints could never have that glory, but of receiving a glorified body and having eternal life, which the man Christ Jesus could have that glory in the beginning before He received it for God calls things that have not happened yet, as though they already happened.
And the saints could behold His glory as He sits on the throne in heaven, and God shines out of the glorified body of the man Christ Jesus and lights the New Jerusalem.