Christological-Pneumatological Infrastructure
Inevitably these matters raise related ones, and I would like to tease out of Calvin's model the following points for consideration. First, a historical-theological point. What I have rehearsed here is only a snapshot of a much larger image of the emergence of the Reformed theological tradition. But it seems to me beyond question that, because what we call "Reformed" has its origins as a distinct perspective on eucharistic union with Christ, we need to appreciate that, with a view to its wide-ranging implications, the Reformed theology of union with Christ lies in significant ways at the theological heart of what it means to be Reformed." Even more particularly, we should recognize that there is such a thing as a Reformed theology of union with Christ, one that has at its core a conviction regarding the economic identity of Christ and the Spirit. It is this christological-pneumatological infrastructure of union with Christ which was cross-applied in sacramental and soteriological contexts in Calvin's theology, and which in just two decades served to distinguish Reformed theology along more than eucharistic lines.
Mark Garcia, "Christology", in Lane G. Tipton and Jeffrey C. Waddington, eds., Resurrection and Eschatology: Theology in Service of the Church (Phillipsburg, NJ: PR Publishing, 2008), 439