As someone who believed medieval Rome taught a piecemeal salvation through a treadmill of sacramental performance, something which he equated in its essence to that of inter-testamental Judaism (aka Pharisaism) as a religion which rung the changes on works-righteousness — seeing both of these as examples of man’s innate tendency to idolatry and self-justification, he would not recognize the New Perspective as doing justice either to the exegesis of Scripture or a diagnosis of man’s real problem. He would regard it as wrongheaded pastorally as well as historically. As one who insisted on double-imputation, he would find the New Perspective’s denial of the imputation of Christ’s righteousness as wholly inadequate to deal with the real problem of fallen (Adamic) man’s relationship to God. As one who made the cross central, he would be perplexed at the inadequate responses of the New Perspective to the question which inquires as to the necessity of the cross or what it actually achieved. Penal substitution through satisfaction were Calvin’s main emphases and a perspective which substitutes ecclesiastical categories (who belongs to the covenant community?) rather than soteriological categories (how can a sinner be made right with God?), and one that answers the former by emphasizing “boundary markers” of baptism and the Lord’s Supper, he would view as Catholicism redivivus.
So claims Derek Thomas. I would like to think that Calvin would have done a better job of understanding the NPP before he dismissed it.