I do not doubt that God's purposes are in their nature eternal, and He purposed the mystery in Christ Jesus. But the church is not spoken of as a purpose before the world. It is a πρόθεσις τῶν αἰώνων, and is εἰς πάσας τὰς γενεὰς τοῦ αἰῶνος τῶν αἰώνων, but not τρὸ τῶν αἰώνων. This is according to His nature and relationship as Father to the Son (but owned in Christ). But it is spoken of, though hidden in the ages, yet only when Christ is raised as men, and so we with Him as man, and so formed by the baptism of the Holy Ghost. Then Christ loved the church; this also is in view of His special relationship with it as a man, second Adam. The Christ gave up all He had to have it and form it for Himself, and present it, glorious, to Himself. Still it is God's assembly; only the Father does not give it to Christ as He does the saints individually. It is an actual thing on earth after Christ's ascension, unrevealed in the ages, in a certain sense not till then (we have Matt. 16), but being revealed in connection with Christ manifested in flesh, not according to the nature of God and the Father. This is full of interest as regards the church. Head over all things is connected with creation and not with God's nature and His being the Father as in Ephesians; that is, it is God's calling, God's inheritance; and then Christ comes in to introduce the church, as raised from the dead, and given to be Head over all things. It is with Him the church is in relationship. Chapter i. 4, 5 is another thing; but all how wonderful! Hence we have operative power from verse 19.
But is not πρ. τ. αί. a purpose, as to the ages, about them, the word πρόθεσις being of God giving the absoluteness of the intention? (Cf. 1 Cor. 2:77But we speak the wisdom of God in a mystery, even the hidden wisdom, which God ordained before the world unto our glory: (1 Corinthians 2:7).) But it was purposed as to the ages, whatever eternity unfolded as to it.