"so that the manifold wisdom of God might now be made known through the church to the rulers and the authorities in the heavenly places."
It is claimed that this passage of Scripture supports the notion of God infallibly making known truth exclusively through a complex church hierarchy (the pope and Magisterium). But does such an interpretation resonate with Paul's thinking in context?
This verse is simply telling us that the underlying point in God redeeming the church is to demonstrate His splendor and majesty to the entirety of creation. The church exists to proclaim the staggering richness of His wisdom through sharing the gospel. His wisdom transcends that of the crafty. His glory transcends that of the wealthy.
The fellowship between Jewish and Gentile believers (as is indicated by their spiritual unity in Christ and His fulfillment of the Mosaic Covenant) serves as a reminder to the devil and his angels of having been conquered. The peace and unity in the truth among Christians is powerful attestation to God's glory throughout creation. Christians should love one another and the truth of His divine revelation.
However, nowhere in context does the author assert that authentic interpretation is given to us through some sort of infallible interpreter. The infallibility of Scripture is not dependent upon the Roman Catholic hierarchy. Scripture is infallible because it was breathed out by God. In other words, it is inherently authoritative. The Holy Spirit moved fallible men to pen infallible writings. He conforms in our hearts the objective internal and external evidences supporting the reliability of Scripture.
The basic assumption of Roman Catholic apologists is that the Roman Catholic Church is true because it said so. There is nothing in Ephesians 3:10 even remotely pointing to the existence of some infallible church hierarchy. That idea has to be read into the text.