Philippians 2:10–11 teaches universal acknowledgment of Christ's authority, not universal salvation.

Here's why, with scripture (NASB):

Philippians 2:10–11:

"...so that at the name of Jesus every knee will bow, of those who are in heaven and on earth and under the earth, and that every tongue will confess that Jesus Christ is Lord, to the glory of God the Father."

This is a clear reference to Isaiah 45:23, where God says:

"To Me every knee will bow, every tongue will swear allegiance."

But in Isaiah 45:24, it continues:

"They will say of Me, 'Only in the Lord are righteousness and strength.' People will come to Him, and all who were angry at Him will be put to shame."

So the acknowledgment is universal, but the response is not. Some rejoice in salvation, others bow in defeat and judgment.

Compare with Romans 14:11–12:

"As I live, says the Lord, to Me every knee will bow, and every tongue will give praise to God. So then each one of us will give an account of himself to God."

That's judgment language, not salvation for all.

And finally, Revelation 20:11–15 shows the dead standing before the throne. They too confess and bow but some are thrown into the lake of fire. Their confession does not result in salvation.

Philippians 2:10–11 describes Christ's universal authority being recognized. It does not mean all are saved. Some bow in joy, others in judgment.