The quote below is from Pastor Holger Sonntag. The bold is all mine, and pay particular attention to what I have bolded in blue:
“The key thing to understanding these verses [Phil. 2] from the epistle reading for Palm Sunday correctly is to read “form of God” not in view of Christ’s divine nature, as if Christ had set aside his divine nature or its powers for the duration of his earthly life. That would be kenoticism.
It is equally wrong to say that, while “form of God” does indeed mean his appearance as God, his divine works and words, the incarnation itself is Christ’s humiliation, as the Reformed say: Because the human nature is incapable of receiving divine attributes, it automatically, as such, works like what Calvin calls a “veil” (Comm. on Phil. 2). For the Reformed, therefore, Phil. 2 could be the epistle reading for Christmas; and indeed, you can find many a Reformed sermon preached on this text in the Advent / Christmas seasons.
When it comes to the means of grace, a different kind of “union” between what is heavenly and what is earthly exists than the personal union of the two natures in Christ. Besides, the means of grace are not all of one kind but must each be understood based on their own specific “words of institution.” However, what is evident is that they, like Christ, are more than what meets the eye or ear. God’s almighty grace and majesty are clothed in a humble, weak creaturely form – whether that be human words, bread, wine, or water – that is administered by a humble man in Christ’s place and that appears foolish to natural man, just like Christ on the cross (1 Cor. 1-2).
This is why God’s grace can only be apprehended there by the heart’s faith in the word, not by the eyes or even by the ears per se. Just as the mouth does not know what it eats and drinks in the Lord’s Supper (Christ’s own body and blood); just as the skin does not know what touches it in baptism (grace-filled water of life), so the ear also does not know what it hears. The heart, however, as the seat of faith, does know from the word it hears and believes; and it is comforted by the fact that so many parts of its body have been touched by God’s grace in view of the future resurrection of the transformed body.
Perhaps surprisingly, Christ instituted the two outwardly lowly sacraments of baptism and the Lord’s Supper and sent his lowly apostles to preach his weak gospel to all creatures near the end of his life on earth – that is, right before and after his death.
Given that the resurrection of Christ is viewed as his transition from the state of humiliation to the state of exaltation – now that his earthly mission to die for sinners is complete, the humiliation of his human nature is no longer needed – some might wonder: shouldn’t Christ in his exalted state have instituted some more, well, “exalted” means of grace that would make our mission on earth easier?
Evidently, Christ’s exaltation does not place Jesus into some automatic “glory-trap” where he must appear the way he appeared on the mount of transfiguration (Matth. 17). So, instead of walking around with a shiny face and bright clothes, he’s easily mistaken as a gardener or some random stranger, even a ghost. What is more, his voice doesn’t sound like the trumpets of Jericho or like the noise surrounding Mt. Sinai when God gave the law to Israel. It’s still the same voice he had before his death and resurrection, which he continues to use to speak to his disciples in a friendly, humble manner. Before and after his resurrection, it is still the voice of divine authority (Matth. 7:29; 28:18-20)….
Christ instituted the means of salvation the way he did for a purpose. What is their purpose? A good way to answer this question is asking a more basic question: What was Christ’s purpose? As we’ve seen, Christ humbled his human nature so that he could make atonement for our sins on the cross (Phil. 2). We also know from the gospels that he humbled himself for those who know themselves to be heavy laden by sin – to them in particular he revealed himself as “gentle and lowly in heart” (Matth. 11:29); in particular to those who were not proud like the wise of this world but humble like little children, he revealed the Father (Matth 11:25-27; 18:3-4; 1 Cor. 1).
The purpose of the gospel fits right here! For its purpose is to deliver Christ’s cross-won grace to sinners terrified by the flashes of divine glory that shine forth in God’s holy law, reflecting, as it were God’s majesty from Mt. Sinai. This means, the gospel cannot be such. Here the divine glory must take on more and different covers than in the law, lest the terrified and humbled be humbled and terrified further – humiliated and scared away from their gentle and lowly Savior.
As we’ve seen already, the gospel in its humble forms is not appreciated by the unbelieving world. These forms are recognized as what they truly are only by faith in the word of God who instituted them for our good, for the good of all sinners humbled by the law. This fate is shared by Christ – he is only recognized as the Son of the living God by divine revelation in God’s word (Matth. 16:17). Without this revelation and the faith that grasps it, the Lord of glory is counted as a common criminal and ends up crucified (1 Cor. 2).
He made himself nothing, we heard from Phil. 2 above. He chose this unappealing, even repulsive form for himself and for the means of his salvation. On the standard religious radars of every time and place and culture, Jesus doesn’t register. His gospel in its divinely instituted forms doesn’t register. It takes an act of God to change this. This act takes place by means of the very forms that are unappealing to the world by nature. There is no way to God’s grace, to knowing God, that bypasses the means of grace the world of unbelievers must find so unappealing to the point of their being a stumbling block.
And why should God’s saving grace be delivered in a form fundamentally different from the form in which it was acquired? Since it was acquired by a man who made himself to be despised by men who looked for majesty and beauty in their savior (Is. 53:2-3), should it not also be distributed in such a form no one by nature will seek out – so that the world’s wisdom and understanding might be put to shame twice, in the act of acquisition of saving grace and in the act of distribution of saving grace?
In the end, this is all about Christ’s mission to save sinners. In order to save those terrified of their sins by the power of the law, and only such he can save by the gospel, he had to take on a form that would not frighten them away from their Savior, speaking to them in a kind and gentle way. He also had to give his means of salvation such a form that would not frighten such sinners away, but that would allow those sinners to hear the kind and gentle voice of their Savior in them clearly.“
(Sonntag, pp. 48-52 bold mine, non-italicized words originally italicized ; again, from the materials given out at the 27th Annual Lutheran Free Conference: “The Character of Christian Worship: It May Not Be What You Think” – Saturday, October 25th, 2014 at Redeemer Lutheran Church in St. Cloud, MN. Full audio available here.)
 Cf. Puritan theologian, Thomas Watson (c. 1620-1686), in his commentary on qu. 27 of the Westminster Shorter Catechism, A Body of Divinity: “‘Q-xxvii: WHEREIN DID CHRIST’S HUMILIATION CONSIST? A: In his being born, and that in a low condition, made under the law, undergoing the miseries of this life, the wrath of God, and the cursed death of the cross.’ – Christ’s humiliation consisted in his incarnation, his taking flesh, and being born. …” Inconsistently enough, Christ’s exaltation is then not equated with the undoing of his incarnation, but with his resurrection (qu. 28).