Phil. 2.6 (KJV) Who, being in the form of God, thought it not robbery to be equal with God:

Phil. 2:6 (ESV) who, though he was in the form of God, did not count equality with God a thing to be grasped.

The word “robbery” in Greek is the word “harpagmon.” Its literal meaning is “robbery” or “plunder.“ However, the fuller context of the verse helps us to further define and understand the word. Since the verse is speaking about Jesus’ deity, in context (Phil. 2:5-11) it seems the word is better understood as meaning “a thing to hang on to at all costs” or simply “grasped.”

For a more complete context let’s add verse 7 to our thought process. Jesus “emptied himself by taking the form of a servant, being born in the likeness of men” (Phil. 2:7). Phil. 2:6-7 doesn’t mean that Christ became anything less than he already was. Christ did not cease to be God in his incarnation. Being fully God, he simply added to his himself a human body. What Paul is stating is that in his incarnation that Christ fully submitted himself to God the Father through the Holy Spirit. Jesus actually illustrates this fact all the way through the book of John. For instance:

John 4:34 Jesus said to them, “My food is to do the will of him who sent me and to accomplish his work.

John 5:19 So Jesus said to them, “Truly, truly, I say to you, the Son can do nothing of his own accord, but only what he sees the Father doing. For whatever the Father does, that the Son does likewise.

John 6:38 For I have come down from heaven, not to do my own will but the will of him who sent me.

So, Jesus temporarily set aside his own life and under the power of the Holy Spirit and absolute obedience to the Father he did the will of the Father and accomplished everything he was ordained to accomplish perfectly. This said, he never ceased being God. Though temporal examples of the divine are limited by earthy illustrations, think of a football as representing God the Son before his incarnation. Now think of the football as having no air in it. Note that the football is still a football but it is emptied of air. Though Christ in his incarnation emptied himself he still remained God.

So, Jesus while remaining God, upon emptying himself became a “slave” to God the Father to do his will (Phil. 2:7). However, prior to his crucifixion Jesus prayed to the Father and says:

John 17:4-5 I glorified you on earth, having accomplished the work that you gave me to do. And now, Father, glorify me in your own presence with the glory that I had with you before the world existed.

So, after his resurrection and in his ascension back to the right hand of God the Father, though remaining fully human, Jesus returned to his former state of not being emptied.