These verses provide the background for Christ's incarnation. The first word we need to consider is form in verse 6. It is the Greek morphe, for which English has no exact equivalent. Unlike "form" in English, morphe does not mean "shape." It is a philosophical term that means "the outward expression of an inner essence." We can derive an illustration of this definition from figure skating. One might say, "I went to the Winter Olympics, and the figure skater's form was outstanding." What is meant is that skater's swift, rhythmic grace, and coordinated movements were an outward expression of his inward ability to skate expertly.
Jesus was in the form (morphe) of God. The word being indicates a condition that began in the past and continues into the present. Therefore, while on earth, the outward expression of His inmost being was the expression of the divine essence, deity. Paul means that when the One who became Jesus, the Word, came to earth to assume the form of a man, He did not cease being God.
Also in verse 6 is the word consider, meaning "to make a judgment based on facts." Paul desires us to weigh the difference between Christ's original state with what He became as a man. He implies that the difference—and thus His humility in making such a sacrifice—is awesome.
The word robbery has two applications: "to seize unlawfully" or "a treasure to be clutched and retained at all hazards." Since the subject of this section is Christ's humility, the second meaning must be the proper application. Christ humbly did not assert His right to consider the expression of His divine essence such a treasure that He should hold on to it at all hazards. He waived that right. This is the very essence of humility.
Finally, God in verse 6 does not refer to a Personage, or it would say "the God" in the Greek. Since it does not, it must refer to deity in general, that is, the expression of the divine essence.
Verse 6, then, declares that, before His incarnation, the Word outwardly expressed His essential nature—Deity—and He judged that being equal with Deity in the expression of the divine essence was not a treasure to be clung to and held at all hazards. Thus, He gave it up to take on another outward expression.
John W. Ritenbaugh
Fully Man and Fully God?