The Church as Sacrament: A Relational Grammar of Mediation, Transparency and Embodied Communion

Vatican II describes the Church as “in Christ like a sacrament” (in Christo veluti sacramentum), a “sign and instrument” of communion with God and of the unity of humankind (Lumen Gentium 1). This article interprets the formula as a relational grammar of ecclesial mediation. Conciliar interpretation, theological genealogy and biblical retrieval show how the Church receives God’s saving gift, participates in it through Christ and the Spirit, and gives it visible, communal form. The article proposes five descriptive dimensions—reception, participation, embodiment, signification and instrumentality—and transparency as a governing critical criterion that tests whether ecclesial practices disclose the mystery they claim to mediate. This is a constructive synthesis, not a taxonomy supplied by the Council. The distinction between gift and ecclesial form also prevents transparency from becoming a measure of grace or sacramental validity. Biblical accounts of communion and deceit sharpen the criterion, while digital worship and artificial intelligence test its practical application. Ecclesial sacramentality thus names an effective yet derived mediation, ordered toward communion and subject to reform.