“. . . making known to us the mystery of his will, according to his purpose, which he set forth in Christ as a plan for the fulness of time to unite all things in Him, things in heaven and things on earth.” (Ephesians 1:9-10, ESV)
The Apostle Paul presents a doxology of praise to Almighty God for who He is and what He has done. These words teach us essential truths in words of thanksgiving, prayer, and praise which edify those who hear them. Paul refers to the Trinity as he addresses Father, Son and the Holy Spirit as the source of every blessing which the believer has. He speaks of our calling by God, our election by Him as saints, His redemption in Jesus, His adoption of us as His sons. God in Christ has done all that man could not do.
Among the great things God has done is to unify mankind. Mankind has been trying to do that since the Tower of Babel but has been only able to produce strife, bloodshed, disharmony and hatred. But God has done it in Christ! This is the mystery of which Paul speaks, a mystery now revealed: the salvation of the Gentiles. Both Jews and Gentiles are equal and they are one for they are united with Christ and so with each other for Christ Himself is the foundation and fullness of the Church. Paul also prays to God for his audience, that they would and understand all the truths he presents and would walk according to them so that they may realize that the fullness of God’s Kingdom is guaranteed. Indeed, in the Church it has already appeared. therefore we must accept all our Christians who are one with Christ for they are one with us no matter what their ethnicity, race, language or nationality.