I thought I might share something of what I shared with the churches in Hawaii.
Unity is ultimately rooted in God’s act for us in Christ. God creates the unity by his own act and we live it out in our concrete situations. Unity is grounded in the divine initative and manifested through divine gifts.
This is the context in which I think about baptism, Lord’s Supper and worship as shared concrete realities through which we experience unity. They are divine gifts through which God mediates his grace and presence. As shared moments/events, we express and experience unity with other believers because God himself is acting in these moments.
Of course, these are not the only moments of God’s acting. Nor are they only moments in which we experience unity or manifest it. Our sanctification–transformed lives of discipleship–also express and manifest unity with other believers as God works in us to conform us to the image of Christ. As we are progressively conformed to that image, we manifest unity (a shared life, a shared discipleship) with others who are also being transformed into that image. But baptism, worship and Lord’s Supper are concrete (empirical) gifts of God that also communally and corporately manifest that unity which God himself created.
God acts through baptism. As we share those waters, our unity rests in the divine work and the divine initiative. Baptism as a means of grace bears witness to God’s work in Christ and mediates the gracious fellowship of the triune God. Through baptism we participate in God’s act in Christ and share the fellowship of the Father, Son and Spirit. As we share that fellowship, we are also in fellowship with all those who participate in that fellowship. The water unites us in a concrete way–not because of the water, but because God has acted to share himself through the water which we all share.
God acts through communal worship. As we assemble, God acts by lifting us up into his presence. The assembled people of God gather around the throne and participate in the holy assembly of the throneroom itself. We draw near to the throne, the city of God. We join the assembly of angels, the assembly of the witnesses of Hebrews 11, and we join the church universal around that throne (Hebrews 12:18ff). God brings us to his throne and gathered around the same throne we manifest the unity that God has created by his act of presence. We are one because we are around the same throne.
God acts through the Lord’s Supper. God is not passive at his table. Rather, he is the active host who invites and calls us to sit a his table in his kingdom. We sit at the same table by divine invitation and initiative. Once again, we manifest the unity that God has created by sharing the same table.
The common thread here is that unity is focused on the divine act, not ours. Our acts manifest the unity that God has created, and these specific acts are divine gifts to humanity for the purpose (at least it is part of the purpose) of experiencing and manifesting that unity. Unity is something God achieves and we manifest. It is not found in the human mechanics of these acts, but in the divine act which gives meaning to the divine gifts through which we bear witness to the unity God has created.