Jonathan Edwards un(?)-Reformed Doctrine of Union With Christ

In Resurrection and Eschatology, there is an essay by Jeff Waddington about Jonathan Edwards' doctrine of justification, which I have particularly found enlightening. I have long been exposed to claims that not only was Jonathan Edwards un-Reformed in his doctrine of justification, but that so was John Calvin (because he believed that justification and sanctification were concurrent blessings to the believer).

Waddington wrote this essay in regard to claims by Thomas A. Schafer that Jonathan Edwards' doctrine of justification was "ambiguous and somewhat precarious." Schafer writes:

In view of the circumstances surrounding Edwards' discourse on justification and its prominence among his first publications, the almost total lack of emphasis on the doctrine in the great works of his last twenty years needs some explanation

So there is innuendo being set forth on Schafer's part that Jonathan Edwards is decidedly non-Reformed in his understanding of justification. Schafer's case is threefold, but I am for the most part interested in the first point of Schafer's which Waddington spends a great deal of time carefully dismantling. The charge which Waddington deals with is the claim that Edwards' doctrine of union with Christ compromises Edwards' Reformed pedigree.

Waddington argues - quite ably - that Schafer has not made his case. Edwards' supposedly troublesome statement is that

what is real in the union between Christ and his people, is the foundation of what is legal; that is, it is something really in them, and between them, uniting them, that is the ground of the suitableness of their being accounted as one by the Judge. (Edwards, Justification by Faith)

As somewhat of an outsider to many of the debates that go on in the Reformed world, I only have a peripheral awareness of certain disputes which are ongoing, and I have recently come to understand that this 'union with Christ' issue is a matter that is fiercely debated today. It is not my place, at this point, to endorse one view or another (since I'm too new to the debate to fairly set out a view of my own). My point here is to affirm Waddington's case that this view of Edwards' is, in fact, not a novelty among Reformed theologians. Waddington quotes Calvin, to support his case, with Calvin discussing the importance of union between believers and Christ:

as long as Christ remains outside us, and we are separated from him, all that he has suffered and done for the salvation of the human race remains useless and of no value to us. (Calvin, Institutes 3.1.1)

Waddington concludes this point in defense of Edwards by stating that, "with John Gerstner, we would argue that his especially clear emphasis on union with Christ only enhances [Edwards'] treatment of justification and gives it a rather solid foundation" (Pg 489).

By the way, I wish to commend to you the entire volume of Resurrection and Eschatology. I have only read a few of the twenty-two essays contained within it, but so far it has all been tremendously instructive. In addition to Waddington's essay which I have been referring to, I have also benefited a great deal from G.K. Beale's essay on the authorship of the book of Isaiah.