Jenson makes the remarkable claim that God is Himself culture (in a contribution to God, Truth, and Witness: Engaging Stanley Hauerwas, 160-1):
“What it is to be God is given in the Father’s eternal begetting of the Son and enlivening through the Spirit, in the Spirit’s eternal liberating of the Father and the Son for one another, in the Son’s eternal self-giving to the Father in the Spirit. Thus the triune God is nothing but culture, and just so is infinite culture, culture setting nature and transforming it and just so setting nature and so on in an eternal act.”
We don’t, in short, encounter God in His “bare” divine nature. We know Him only in the “social” interactions of Father, Son, and Spirit, which are “cultural” interactions of ritualized self-gift.
And this cultured God makes Himself available in a culture: “If the church is the body of Christ, that is, if the church is the availability of Christ in and for the world, and if this body of Christ, the church, is a culture, it follows then that Christ is a culture. And the sense of the ‘is’ in ‘Christ is a culture’ will be the sense in which each of us must say that he or she ‘is’ his or her body” (“Christ as Culture,” IJST 5  325).
To confess the Trinity then is to also confess the church. And perhaps there is an implicit Trinitarian heresy in theologies that deny the necessary mediation of the structured Eucharistic community.