Yes, Jesus Christ is truly and eternally God, the second person of the Trinity, co-equal and co-essential with the Father. Reformed and orthodox Christian tradition affirms that He is not a created being, but the very Son of God who assumed human nature to become our Mediator.
The Holy Scriptures consistently reveal that Jesus is not a creature, but the eternal Word of God. As the Belgic Confession Art. 10 states, He is the 'only begotten Son of God, begotten from eternity, not made nor created... but co-essential and co-eternal with the Father.' The Apostle John opens his Gospel by grounding this truth in the very nature of Christ's existence: John 1:1. This confirms that the Savior we trust in is not merely a man or an angel, but the very Creator of all things.
While Christ is truly God, the gospel also requires that He be true man to serve as our Mediator. In the Institutes of the Christian Religion Bk. II Ch. 12 §1, Calvin notes that it was necessary for the Godhead to 'descend to us,' as we could not ascend to Him. By becoming our Emmanuel—God with us—Jesus Christ is the one 'Mediator between God and man' (1 Timothy 2:5). He unites His divinity and humanity in one person, so that as our High Priest, He can represent us before the Father and pay the penalty for our sins in the very nature that sinned.