I wish to address this also, as it has not been raised before, and has on the surface some merit for the trinitarian view point. But this article explains it better than I can.
Philippians 2:6-11 Jesus in the form morphe of God
To address the link:
2. The context of this passage must be carefully considered. Paul does not just start talking about Jesus ‘out of the blue’. He refers to the mind of Jesus in Phil. 2:5. Back in Phil. 1:27 Paul starts to speak of the importance of our state of mind. This is developed in the early verses of chapter 2: “Being of one accord, of one mind...in lowliness of mind...look not every man on his own things, but every man also on the things of others. Let this mind be in you, which was also in Christ Jesus...†(Phil. 2:2-5). Paul is therefore speaking of the importance of having a mind like that of Jesus, which is devoted to the humble service of others. The verses which follow are therefore commenting upon the humility of mind which Jesus demonstrated, rather than speaking of any change of nature. Just as Jesus was a servant, so earlier Paul had introduced himself with the same word (Phil. 1:1 cp. 2:7). The attitude of Jesus is set up as our example, and we are urged to join Paul in sharing it. We're not asked to change natures; we're asked to have the mind of Jesus- so that we may know the "fellowship of sharing in his [Christ's] sufferings, becoming like him in his death and so to attain to the resurrection from the dead" (Phil. 3:10,11).
The author is right that the context is being humble, just as Christ was:
Php 2:3 Do nothing from rivalry or conceit, but in humility count others more significant than yourselves.
Php 2:4 Let each of you look not only to his own interests, but also to the interests of others.
Php 2:5 Have this mind among yourselves, which is yours in Christ Jesus,
......
Php 2:12 Therefore, my beloved, as you have always obeyed, so now, not only as in my presence but much more in my absence, work out your own salvation with fear and trembling,
Php 2:13 for it is God who works in you, both to will and to work for his good pleasure.
Php 2:14 Do all things without grumbling or questioning, (ESV)
However, the author clearly misses the thrust of Paul's argument: it is
precisely because Jesus was, in nature, God, that we see his humility in becoming human. It is impossible to show more humility than that. That is what we are to consider so that we become humble.
3. Jesus was “in the form of Godâ€. We have shown in an earlier study that Jesus was of human nature, and therefore this cannot refer to Christ having a Divine nature.
Begging the question, which then filters down some subsequent arguments which I will not address.
That “form†(Greek ‘morphe’) cannot refer to essential nature is proved by Phil. 2:7 speaking of Christ taking on “the form of a servantâ€.
Incorrect. Being in "the form of a servant" is equivalent to "being born in the likeness of men," meaning that he had a human nature. And so it is with being "in the form of God."
Remember, Paul is contrasting the two to show just how humble Christ was. If being "in the form of a servant" means he had a human nature, so "being in the form of God" means he had a divine nature, in some way (see below).
The Greek word ‘morphe’ means an image, impress or resemblance. Human beings can have a ‘morphe’. Gal. 4:19 speaks of “Christ (being) formed in†believers. Because he had a perfect character, a perfectly God-like way of thinking, Jesus was “in the form of Godâ€. Because of this, Jesus did not consider equality with God “something to be grasped atâ€. This totally disproves the theory that Jesus was God. Even according to the N.I.V. translation, Jesus did not for a moment entertain the idea of being equal with God; he knew that he was subject to God, and not co-equal with Him. There are many examples in the Greek Old Testament of the Greek word morphe being used to mean 'outward form' rather than 'essential nature'- e.g. Jud. 8:18 [men had the morphe , the outward appearance, of a king's sons]; Job 4:16 ; Is. 44:13 [a carpenter makes an idol in the morphe or outward appearance of a human being- but not in the very nature of a human being!]; Dan 3:19 [the king's morphe or appearance changed because he got angry; his essential nature remained the same]. And likewise in the Apocrypha: Tobit 1:13; Wis. 18:1; 4 Macc. 15:4. If Paul meant nature or essence he would have used the word ousia or physis- as he does in Gal. 2:16 where he speaks of "We who are Jews by nature [physis]...".
From Vincent's Word Studies:
Being. Not the simple είναι to be, but stronger, denoting being which is from the beginning. See on Jam_2:15. It has a backward look into an antecedent condition, which has been protracted into the present. Here appropriate to the preincarnate being of Christ, to which the sentence refers. In itself it does not imply
eternal, but only
prior existence. Form (μορφή). We must here dismiss from our minds the idea of
shape. The word is used in its philosophic sense, to denote that expression of being which carries in itself the distinctive nature and character of the being to whom it pertains, and is thus permanently identified with that nature and character. Thus it is distinguished from σχῆμα
fashion, comprising that which appeals to the senses and which is changeable. Μορφή
form is identified with
the essence of a person or thing: σχῆμα
fashion is an accident which may change without affecting the
form. For the manner in which this difference is developed in the kindred verbs, see on Mat_17:2.
As applied here to God, the word is intended to describe that mode in which the essential being of God expresses itself. We have no word which can convey this meaning, nor is it possible for us to formulate the reality.
Form inevitably carries with it to us the idea of
shape. It is conceivable that the essential personality of God may express itself in a mode apprehensible by the perception of pure spiritual intelligences; but the mode itself is neither apprehensible nor conceivable by human minds.
This mode of expression, this
setting of the divine essence, is not
identical with the essence itself, but is
identified with it, as its natural and appropriate expression, answering to it in every particular. It is the perfect expression of a perfect essence. It is not something imposed from without, but something which proceeds from the very depth of the perfect being, and into which that being perfectly unfolds, as light from fire. To say, then, that Christ
was in the form of God, is to say that He existed as essentially one with God. The expression of deity through human nature (Phi_2:7) thus has its background in the expression of deity as deity in the eternal ages of God's being. Whatever the mode of this expression, it marked the being of Christ in the eternity before creation. As the
form of God was identified with the
being of God, so Christ, being in the form of God, was identified with the being, nature, and personality of God.
This
form, not being
identical with the divine essence, but dependent upon it, and necessarily implying it, can be parted with or laid aside. Since Christ is one with God, and therefore pure being, absolute existence, He can exist without the form. This form of God Christ laid aside in His incarnation.
Clearly, one cannot say that if Paul meant "this" he would have used such-and-such a word. That is an exegetical error on the part of the author.