There are constraints on what counts as "Reformed." It's more than a name or a label. It's about belonging to a particular theological stream or tradition, which is shaped in important respects by particular thinkers and their work, particular arguments and ideas, a particular community (especially, particular church communities, denominations, and so on), particular liturgies or ways of worshipping and living out the Christian life, and particular confessions that inform the practices of these communities.

The Reformed tradition at the beginning of the twenty-first century is different as a consequence of this - and different in nontrivial ways. Some may scoff at this, saying that such "developments" don't represent Reformed thought. But by what standard? Perhaps by the Westminster Confession. But this is only one Reformed confession, and it was only ever a subordinate standard.

How many people in the pews know that [ Jonathan Edwards] is both a founder of evangelicalism and, say, an idealist who denied that the material world exists?

In the twentieth century the Reformed tradition was developed in several ways including additional confessions (Barmen, the Belhar Confession, the 1967 Confession of the PC(USA), and so on). It was also significantly augmented by the work of important thinkers like Karl Barth, T. F. Torrance, Jürgen Moltmann, Emil Brunner, Kathryn Tanner, and so on.

[Jonathan] Edwards definitely shows up in the book [Saving Calvinism]. He appears as one of the interlocutors in the chapter on free will, the other being the Southern Presbyterian theologian John Girardeau.

Jonathan Edwards developed a Calvinistic strand of the doctrine.

It is often reported that the Five Points of Calvinism are the conceptual hard-core of Reformed thought. That is very misleading. The Five Points supposedly originate with the Synod of Dort in the early seventeenth century. Yet we find important Reformed leaders who were signatories to that documentation who don't think that limited atonement is the right way to think about the scope of Christ's saving work. How can this be? The answer that recent historical theology has thrown up is that the canons of the Synod don't require adherence to the doctrine of limited atonement.