“who, though he was God in essence, did not regard it as something to be grasped — to be equal to God — ”
This is one of those verses, when taken in isolation of the teachings of scripture and not with an understanding of the Greek language, has led people down the road to heresy, for some will read this verse as saying that Jesus gave up his divinity to become human and such could not be further from the truth. In addition, there are also some who will read this verse in a way that implies that God the Son and God the Father are separable. Similarly, this is not the testimony of scripture as a whole.
Paul’s words in this verse begin with, “though he was God in essence.” Some of our English translations render this: “though he was in the form of God,” which is good Greek, but can be misleading in English. For us, something that takes the form of something else is a doppelgänger of sorts — a mimic or a copy, but not one with the original. The term that Paul uses here is morfh/ (morphe), which refers to the basic essence of something. Essentially what Paul is writing here is that all of the essential attributes of the Godhead were and are fully present in Jesus. In fact, given that the verb in this clause is in the imperfect state, the implication is that these divine attributes continue even into his dual nature. Jesus is God…he is the second person in the Triune Godhead, and he did not consider, reason, or think that his rightfully revealed glory was something to be clung to but he came to this world in the essence of a servant…a slave even.
Interestingly, Jesus’ behavior is just the opposite of Satan who was willing to sacrifice everything in the hopes of becoming equal in status with God yet was thrown down because of his rebellion. Satan demonstrates the results of pride; Jesus demonstrates a life of humility. How often, in life, even professing Christians pursue a life that looks more like Satan’s than Jesus’. And what is this language of equality at the end of the verse? It speaks not to ontological equality (equality in essence, something that has already been established) but to equality in status or glory…such would be the contrast that Paul is establishing in the following verse. There is an exchange not in essential Godhead but instead a willingness to veil his glory in the flesh of humanity for a season and for the purpose of saving humanity. What a mighty and great God we serve!