Richard Gaffin nails it in one of his concluding statements to his book on the resurrection in Paul's soteriology.
Not justification by faith but union with the resurrected Christ by faith (of which union, to be sure, the justifying aspect stands out perhaps most prominently) is the central motif of Paul's applied soteriology.
Gaffin footnotes Jonathan Edwards, who had written:
What is real in the union between Christ and his people, is the foundation of what is legal; that is, it is something that is really in them, and between them, uniting them, that is the ground of the suitableness of their being accounted as one by the judge.
--Richard Gaffin, Resurrection and Redemption: A Study in Paul's Soteriology (2d ed.; P&R 1987), 132