Recent ecumenical dialogues have focused on the question of ecclesiastical offices. At the heart of this debate lies the question of how to relate the Holy Spirit's guidance of the church to its structures. Two alternative visions frame the debate. The Roman Catholic Church insists on the authority of the church's teaching office, as the channel through which the Holy Spirit guides the church. In contrast, Protestant churches emphasize the self-sufficiency of scripture, the normative function of the Gospel vis-à-vis the church, and the freedom of the Holy Spirit in, with, and over against all ecclesiastical structures. My essay engages this ecumenical debate through fundamental ecclesiological reflections on the relation between the Holy Spirit on the one hand, and the scriptural witness and ecclesial authority on the other. I argue that no ecclesial structure must be identified undialectically with the voice of the Holy Spirit, but that the church must discern the guidance of the Spirit in the context of the Christian assembly, as it emerges ever anew from the “gaps” left open in the assembly's juxtapositions of texts, bath, and shared meal. In order to develop my thesis, I first retrieve Karl Barth's christological foundation of ecclesiology, his definition of divine freedom over against the church, and his introduction of scripture as the critical principle for the church's permanently needed self-reform. Second, I discuss Walter Kasper's insistence on the incarnational and sacramental nature of the church and his threefold understanding of the church's apostolicity in terms of succession, tradition, and communion. Finally, I develop Gordon Lathrop's reading of the Christian assembly of worship in terms of liturgical juxtapositions for my ecclesiastical purposes.