When earnest striving to grow disappears, so does church unity. We begin with God and what He has done, but we cannot, like the Eastern Church tends to do, stop with contemplation on His nature. We must seek to become like Him. The unity of Christian people is to reflect the unity of the Godhead. But Christian unity is not metaphysical in the same way that the unity of the Persons of the Trinity is, though there is a metaphysical side to it in so far as we are all indwelt by the same Spirit of God.
Ethics here is primary.
The unity of the Trinity includes the personal harmony of love and righteousness, as well as unity of purpose and work. It is this aspect of the unity of the Godhead that the Church is called to reproduce. We are striving for Godlikeness because we love Him. God Himself is the center of our vision, the standard of our ethics, the motive and the goal of all our work. The unity and diversity of God's people is to reflect the perfect harmony of love and diversity of working in Persons of the Trinity.