Note the phrase “plan of the mystery hidden for ages in God who created all things,” by apostle Paul:
“To me, though I am the very least of all the saints, this grace was given, to preach to the Gentiles the unsearchable riches of Christ, and to bring to light for everyone what is the plan of the mystery hidden for ages in God who created all things, so that through the church the manifold wisdom of God might now be made known to the rulers and authorities in the heavenly places.” (Ephesians 3:8)
It’s inevitable: Every tongue will confess & every knee will bow to swear [allegiance] to the Saviour in Love at the (kairos) ‘appointed time’ of their salvation —> leading eventually to God being “all in all” (the world saved and creation perfectly restored in Him).
That’s the Mystery of Christ in the Secret of His Will who created & framed the ages (of time) for His Good Purpose in Himself in order to gather in One all things back to Him.
‘Blessed Saviour of the World’