What does Ephesians 3:11 mean?

This mystery which God has revealed regards Jews and Gentiles as one (Ephesians 3:1–10). Though not fully explained until now, this is not a new idea God dreamed up. He did not invent this plan at the last minute, but rather knew about it in eternity past. Some Scriptures imply God's intentions before "the foundations of the earth" (Proverbs 3:19; Job 38:4; Isaiah 48:13) Here, Paul notes that this it was part of God's eternal purpose. God has always known His plan and revealed it exactly as prepared. God's plans are not only known, but He "works all things according to the counsel of His will" (Ephesians 1:11).

This plan was "realized in Christ Jesus our Lord." In other words, the mystery was revealed through Jesus. He is the Messiah and fulfillment of past prophecies concerning the Coming One, God with us (Emmanuel), and the Suffering Servant (Isaiah 53). It is through Jesus that salvation has been provided equally for both Jew and Gentile, not through the law, but through faith (Ephesians 2:8–9).