In the continuation of the thought in the last verse, Paul reminds us that it was always the will of God to reveal in total this teaching on the combination of the Jews and Gentiles into one body of believers. He will speak more to the understanding in Colossians 2:2 (UASV) where he refers to Christ as “the mystery of God, namely Christ.”
Paul’s supreme joy is to extend his divinely imposed obligation of sharing this truth. He says that he is sharing with the Gentiles the truth of what they have. He wants them (and us) to understand the splendor and majesty of the abundance (Greek ploutos) that we have received. That is the blessing and opulence of having Christ in us. This phrase can carry a double meaning. It is an idiom that Paul is using that can be understood to mean that Christ is in the individual or that He is in the midst of the collective. In the setting of the letter, it appears that Paul is foremost meaning that the Gentiles have Christ living in them individually.
The importance of this knowledge gives the Gentile believer a hope (Greek elpis) which means a joyful and confident expectation. This confident expectation is that they now have “his risen life within them… [affording] them a stable basis for confidence that they will share in the fullness of glory yet to be displayed on the day of ‘the revealing of the sons of God’ (Rom. 8:19)”
 Bullinger, E. W. (1968). Figures of Speech used in the Bible. Grand Rapids, Mich., USA: Baker Book House. Page 831.
 W. E. Vine, Merrill F. Unger and William White, Vine's Complete Expository Dictionary of Old and New Testament Words (Nashville, Tennessee: Thomas Nelson, Inc., 1996). Page 311.
 Bruce, F. F. The Epistles to the Colossians, to Philemon, and to the Ephesians. Grand Rapids: Eerdman's Publishing Co, 1984. Page 86.