Though most probably think of predestination as the ultimate distinctive of the Reformed faith, those who talk the most about Reformed predestination are the non-Reformed. Within Reformed theology, while predestination is a foundational doctrine, it's not a doctrine from which other doctrines flow. For that we can turn to Christological-Pneumatology.
This isn't a new concept, but the 20th century was a time when people grew tired of endlessly long book titles and the needing to describe each concept each time, so acronyms abounded and new theological terminology was created.
Within the properly Reformed, there's widespread diversity. The confessions, for example, are lowest-common denominators, not exhaustive systematic theologies. Jeffery Jue reminds us:
...any seventeenth-century doctrine must be examined within a nexus of theological opinions and articulations (and doctrinal solidarity may vary from issue to issue) in order to understand the motivations and intentions of various English divines.2
Compare Sinclair Ferguson:
...within generic Reformed theology there has always been a diversity of viewpoint on various issues. Being aware of this saves us from naïvely (but dogmatically!) saying, “The Reformed view is . . . ,” when all we are entitled to say is, “The view held by a number of Reformed writers with whom I agree is . . .”!3
However, at the core of the Reformed branch of the reformation was Christological-Pneumatology. It's the sine qua non of Reformed branch as its our understanding of the Supper. It's ultimately that which capitalizes the R.
Mark Gracia helps us here:
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.1
What is Christological-Pneumatology? It's ultimately the fact that the presence of the Spirit is the presence of Christ.
To speak of Pneumatology is to speak of Christological-Pneumatology. Hear Richard Gaffin:
In the end, "Reformed Charismatic" is both a contradiction and an oxymoron depending on the context.