I appreciate your taking the time to explain this further! I wished to have responded earlier but have been tied up with other things.
Both Philippians 2:10-11 and Romans 14:11 cite Isaiah 45:23, so I think it is worth examining the latter text in its context.
“Assemble yourselves and come; draw near together, you survivors of the nations! They have no knowledge who carry about their wooden idols, and keep on praying to a god that cannot save. Declare and present your case; let them take counsel together! Who told this long ago? Who declared it of old? Was it not I, the LORD? And there is no other god besides me, a righteous God and a Savior; there is none besides me. “Turn to me and be saved, all the ends of the earth! For I am God, and there is no other. By myself I have sworn; from my mouth has gone out in righteousness a word that shall not return: ‘To me every knee shall bow, every tongue shall swear allegiance.’ “Only in the LORD, it shall be said of me, are righteousness and strength; to him shall come and be ashamed all who were incensed against him. In the LORD all the offspring of Israel shall be justified and shall glory.” - Isaiah 45:20-25 (ESV)
In these verses, the prophet is speaking to all the nations (v20) and telling them to assemble (v20), come (v20), draw near (v20), declare and present their case (v21), and turn and be saved (v22) by the God of Israel. Isaiah declares “every knee shall bow, every tongue shall swear allegiance” (v23), but does not require, in context, that such bowing and swearing be willfully penitent submission to the Lord. In fact, he goes on to distinguish between those who are the enemies of God (“incensed against him”) and those who are the elect of God (“offspring of Israel”), the former being ashamed by their rebellion and the latter being justified and glorified. Isaiah is prophesying of the supremacy and authority of God over all things.
Paul quotes this passage in two places. In Philippians he writes:
Have this mind among yourselves, which is yours in Christ Jesus, who, though he was in the form of God, did not count equality with God a thing to be grasped, but emptied himself, by taking the form of a servant, being born in the likeness of men. And being found in human form, he humbled himself by becoming obedient to the point of death, even death on a cross. Therefore God has highly exalted him and bestowed on him the name that is above every name, so that at the name of Jesus every knee should bow, in heaven and on earth and under the earth, and every tongue confess that Jesus Christ is Lord, to the glory of God the Father. - Philippians 2:5-11 (ESV)
That Christ condescended from heaven, took on flesh, obeyed the Father’s will, and bore the curse of sin and death on the cross was the means by which he was exalted to the right hand of the Father. In his exaltation he rules as the King of kings and Lord of lords so that all will ultimately bow and confess that truth to the glory of God. Paul uses these Scriptures to show that the Jesus is the Lord (Yahweh) which Isaiah had declared. He does not quote Isaiah to demonstrate the eschatological state of all people who have ever lived, but to show the divinity of Christ and his supremacy over all of creation. He is Lord of all, and all will confess this truth whether they are his enemy or his friend.
In Romans, Paul again quotes the prophet:
For to this end Christ died and lived again, that he might be Lord both of the dead and of the living. Why do you pass judgment on your brother? Or you, why do you despise your brother? For we will all stand before the judgment seat of God; for it is written, “As I live, says the Lord, every knee shall bow to me, and every tongue shall confess to God.” So then each of us will give an account of himself to God. Therefore let us not pass judgment on one another any longer, but rather decide never to put a stumbling block or hindrance in the way of a brother. - Romans 14:9-13 (ESV)
Here he is addressing the Roman saints as to Jewish customs. Should the Roman Christians adhere to these customs or not? To that end, Paul tells his brethren not to judge each other so as not to be a stumbling block for those who are weak in faith. He quotes Isaiah to show them that the Lord will ultimately act as judge of all. They are to show brotherly love for each other because they are accountable before him. It does not appear to me that Paul is using Isaiah here to point to any kind of universal reconciliation. Rather he quotes the words of the prophet to demonstrate that the Lord has sole authority to finally judge all those who stand before him, not that all who bow and confess will be regarded as saints.
Finally, John’s vision in Revelation:
And when he had taken the scroll, the four living creatures and the twenty-four elders fell down before the Lamb, each holding a harp, and golden bowls full of incense, which are the prayers of the saints. And they sang a new song, saying, “Worthy are you to take the scroll and to open its seals, for you were slain, and by your blood you ransomed people for God from every tribe and language and people and nation, and you have made them a kingdom and priests to our God, and they shall reign on the earth.” Then I looked, and I heard around the throne and the living creatures and the elders the voice of many angels, numbering myriads of myriads and thousands of thousands, saying with a loud voice, “Worthy is the Lamb who was slain, to receive power and wealth and wisdom and might and honor and glory and blessing!” And I heard every creature in heaven and on earth and under the earth and in the sea, and all that is in them, saying, “To him who sits on the throne and to the Lamb be blessing and honor and glory and might forever and ever!” And the four living creatures said, “Amen!” and the elders fell down and worshiped. - Revelation 5:8-14 (ESV)
The doxologies within this section (v9-10, 12, 13) show that the Lamb, and he alone, is worthy of all blessing, honor, and glory. In this setting, these verses point to the redemptive work of the triune God through Christ and the undeniable recognition of him as King of creation. I do not think that the doxologies are soteriologic but Christologic. That is, they proclaim the glory of God in redemptive history through Jesus Christ.
I do have a question to which I am curious to hear your thoughts. In light of your interpretation of the passages referenced in your post, would you hold that Satan and his angels will eventually be reconciled to God? For example, in Philippians, Paul states that every knee in heaven, on earth, and under the earth will bow. Would you consider this inclusive of the spiritual realm and thus indicative of the ultimate redemption of the fallen spirits?
