Gordon Fee writes about Philippians 2:5-11:

Christ’s selflessness for the sake of others expressed itself in his emptying himself by taking the “form” of a slave.  Historically, far too much has been made of the verb “emptied himself” of something.  However, just as harpagmos requires no object for Christ to “seize” but rather points to what is the opposite of God’s character, so Christ did not empty himself of anything; he simply “emptied himself,” poured himself out, as it were.  In keeping with Paul’s ordinary usage, this is metaphor, pure and simple.  What modifies it is expressed in the phrase that follows; he “poured himself out by taking on the ‘form’ of a slave.”

Elsewhere this verb regularly means to become powerless or to be emptied of significance (hence the NIV’s made himself nothing; cf.KMV, “made himself of no reputation”).  Here it stands in direct antithesis to the “empty glory” of verse 3 and functions in the same way as the metaphorical “he became poor” in 2 Corinthians 8:9.  Thus, as in the “not” side of this clause (v. 6b), we are still dealing with the character of God as revealed in the mindset and resulting activity of the Son of God.  The concern is with divine selflessness:  God is not an acquisitive being, grasping and seizing, but self-giving for the sake of others.  Gordon Fee, Philippians, The IVP New Testament Commentary Series, p. 94-95.

Stirs up worship doesn’t it?

This is Our God: