Because Jesus is God (Jn. 1:1), He is eternal; as God, He created and sustains all that exists (Gen. 1:1; Jn. 1:1-3; Col. 1:16-17; Heb. 1:1-2; etc.)! Because He is God, He shared equally in the glory of His Father before He created the world (Jn. 17:5; Phil. 2:5-6; etc.).
Because He pre-existed His Incarnation, John the Baptist, Christ's older cousin, could say, "This was He of whom I spake, He that cometh after me is preferred before me: for He was before me" (Jn. 1:15, 30)! This paradoxical statement can be understood only as we distinguish between the two natures of Christ. When viewed from the standpoint of His humanity, He came after John the Baptist. Mary gave birth to Him six months after Elizabeth had given birth to John, but as the eternal Son of God, He was before John the Baptist, eternally existing in the bosom of the Father (Lk. 1:24-37; Jn. 1:18).
Perhaps the Savior, Himself, made the clearest statement of His pre-existence. Speaking with a group of unbelieving Jewish religious leaders, He said, "Your father Abraham rejoiced to see My day: and he saw it, and was glad" (Jn. 8:56). These Jews were startled by these words, understanding Him to be saying that He and Abraham existed on this earth at the same time: "Then said the Jews unto Him, Thou art not yet fifty years old, and hast Thou seen Abraham?" (Jn. 8:57). They knew that Abraham had lived and died approximately 2000 years earlier! How could this Man claim to be 2000 years old? They were shocked and angered by the Lord's final words: "Jesus said unto them, Verily, verily, I say unto you, Before Abraham was, I am" (Jn. 8:58). They considered this to be ultimate blasphemy, and they "took up stones to cast at Him" (Jn. 8:59).
Only the eternal God could make such a claim. Indeed, Jesus could have even said, "Before Adam was, I am!" He even could have said, "Before the universe was, I am!" In fact, He did make such a statement: "And now, O Father, glorify Thou Me with Thine own self with the glory which I had with Thee before the world was...for Thou lovedst Me before the foundation of the world" (Jn. 17:5, 24). God the Son basked in the sunlight of the Father's love before the world ever was! From everlasting to everlasting, He is the Son of the Father's love. The eternal Son is worthy of all glory and praise and adoration!
By trusting in the true Jesus, you are literally trusting in God!