No Naaji,
Jesus has not always existed on this planet. He was born somewhere around 6BC and he died sometime 33 years later.
Now having said that, there has never been a time when He was not, or never will be a time when He won't be. You see, the Jesus we saw on the earth , WAS God, but God come in the flesh. He wasn't created at birth, if that were the case, Christians would be guilty as charged of following more than one God.
When Jesus was born.. He became God incarnated.. that is He chose to limit Himself as God and come to earth as man FOR THE PERIOD OF TIME HE WAS ON EARTH. Yet whilst limiting Himself, HE NEVER STOPPED BEING GOD.
Now remember, His Disciples and followers were all Jews and like Muslims, had come from being taught from birth that "There is only ONE true God".. yet they accepted and worshipped Jesus as God come in the flesh.
The New Testament forbids worship of angels, yet commands worship of Jesus and focuses on Him as the proper object of faith, hope and love.
All this took place to fulfill what the Lord had said through the prophet:
“The virgin will be with child and will give birth to a son, and they will call him Immanuel”—which means, “God with us.” (MATTHEW 1:22-23)
Matthew 1:18-25 and Luke 1:26-56; 2:4-7, two harmonious and complementary but obviously independent stories, unite in witnessing to Jesus’ birth as the consequence of a miraculous conception. Mary became pregnant by the Holy Spirit’s creative action without any sexual relationship (Matt. 1:20; Luke 1:35).
In reality, the Virgin Birth meshes harmoniously with the rest of the New Testament message about Jesus.
He himself worked miracles and rose miraculously from the dead, so no new problem is involved in affirming that he entered the world miraculously. He left the world supernaturally, by resurrection and ascension, so a supernatural way of arriving was entirely fitting. The stress laid on Jesus’ preincarnate dignity and glory (John 1:1-9; 17:5; 2 Cor. 8:9; Phil. 2:5-11; Col. 1:15-17; Heb. 1:1-3; 1 John 1:1) made a mode of entry into incarnate life that involved proclamation of the glorious role he was coming to fulfil (Matt. 1:21-23; Luke 1:31-35) more natural than any alternative.
(these quotes are from Title: Concise Theology: A Guide To Historic Christian Beliefs
Author: Packer, J.I. (James Innell)
Never once did Jesus exhort men to worship him whilst he was on the earth. Always He ensured and focused men to worship only the God of Abraham, Isaac and Jacob. Isn't it strange, that He who billions call God, channelled all praise, honour and glory to God His Father?
Now, having discussed that Jesus pre-existed his appearance on earth and is God, the rest of your question/comment is easy to answer.
Is the Word of God eternal? The Greek word used for Word of God is the "Logos" which literally means "the expression of thought, not the mere name of an object" When used in relation to Jesus as the Word of God in John 1 it declares Jesus' distinct and superfinite personality. He wasn't just speaking out the word of God.. he was it's expression. He was what his words had said from eternity past He was and what he demanded of the world it should be. His was the Shekinah glory in open manifestation..
He was/is as it says in Hebrews 1:3 the radiance of God's glory, and the EXACT representation of his being, sustaining all things by His word.
Proverbs 8:22-36 speaks of wisdom being present when God called the universe into being and states "For whoever finds me finds life and receives favour from the Lord, whoever fails to find me harms himself all who hate me love death.
The Bible uses different metaphors to describe one who was with God and was one with God at the beginning.. Wisdom is one, and Word is the other.
David in Psalm 119:89 declared
"your word, O Lord, is eternal. It stands firm in the heavens."
Isaiah 40:8 states "The grass withers and the flowers fall, but the Word of our Lord stands forever"
The Word of God is eternal. God cannot change and His Word therefore cannot change either. Jesus is called the Logos of God.. the exact representation of His glory, the manifestation of all his being.
The Logos of God invaded our planet for one supreme purpose. To save a lost race from eternal ruin. For us, and for our salvation, God became in all respects man. Why? this we find in Hebrews 2:9-18
1. That He might taste death (the wages of sin) for every man. His death was substitutionary. He died that we might live
2. That He might bring many sons to glory. Christ descended to earth, so that we could ascend to Heaven to be with Him forever.
3. That He might set us apart as his brothers. Christ's coming opened a new door of relationship between man and God. We are now no longer his enemies, but members of His family.
4. That he might destroy the power of the devil. This was the only way we could be freed from the bondage to sin
5. That we might be delivered from the torment of death. No believer fears the sting of the grave.
6. That He might become the perfect high priest for the propitiation (sacrifice that turns away the wrath of God) of sins.
The second person of the Godhead entered the world, not out of curiosity, nor out of any sense of personal need. The Father sent the Son on an errand of mercy solely to accomplish man's redemption.
Since Man was created by the Word of God it was fitting that fallen man should be recreated by the same Word (compare John 1:3 with John 3:17)
Naaji, when christians talk of Jesus being God.. we don't talk of a man with a beginning and end who we worship as God.. that would be pure blasphemy. We talk of God who became man so that He could bring us to back to full relationship with God. When we worship Jesus, we are not worshipping a man. We are worshipping the ONE and ONLY God.