Did you ever know everything that God is, the Word is? Jesus is essentially equal with God because He possesses the fullness of the attributes of God! which means that, Who God is, The Word is. What God can do, the Word can do! ( Philippians 2:6-8, John 1:1)
When Jesus came into the world, though He was essentially God He was not eager to hold unto that attribute of being God. What He did was, He stripped Himself of all privileges and rightful dignities (Pouring out himself; his Deity, Power, Glory etc known as Kenosis) He did this, so that he can assume the guise of a servant, in that He became a man and was born a human being (Philippians 2:7). Hallelujah!!!!!
The mystery of Jesus's entry into the world was to confirm that, a group of people who are like Christ will show up known as Christians (Christ-like) and also it was to tell the world that in some time to come He's going to have other Jesus's! Glorrrrrrrryyyyyyy!