Guelzo's story starts with eighteenth-century Anglicanism and the US Protestant Episcopal Church hewing to their Reformed theological roots, hospitable to evangelicalism, with an episcopal polity working as an effective means of governance. The Oxford Movement served as a distraction, dangling a bright, shiny object of Ritualism in front of churchmen who'd lost sight of their evangelical mission. One difficulty that Guelzo points out is that, by leaving PECUSA, the REC also abandoned the rationale for bishops or a stable theology as outlined in the XXXIX Articles, which later national conventions wished to amend to XXXV. But if you get right down to it, the REC was true to its Reformed origins in doing so.
Guelzo in fact gave me a refresher on my Presbyterian confirmation class, which was largely anti-Catholic propaganda. Only two sacraments are authorized in scripture, and the Catholics have bizarre ideas that marriage and ordination should be sacraments, to say nothing of -- aaargh! -- confession. The actual sacraments are just sort of a declaration of intention and a memorial anyhow. Bishops are an outdated medieval and anti-democratic institution. We are saved by grace, not by works. Guelzo takes things a step farther to remind us that in Reformed theology, all believers are priests, and what Catholics mistakenly call a "priest" is just a presbyter. Vestments are just vain display.
This is a mindset. I look back on my elite-school education, which, while nominally secular, retained a great deal of Reformed world-view: if doctrine and liturgy are obstacles to the true working of the Spirit, then the sincerity of your intent overrides outward appearances, which are hypocritical anyhow. Thus we got the 1960s in all their aspect. True religion, for that matter, is something that's only partly manifested in outward forms like creeds or crucifixes. In fact, Buddhism in that way is much more pure than Christianity -- something I believed myself for several years there.
To come out of this was a journey. Something similar, for that matter, was a journey for St Augustine. And it was a journey for Reformed converts like Peter Kreeft, Scott Hahn, and David Campbell. Hahn and Campbell resigned their Presbyterian orders, in fact, and became Catholic lay apologists. This reinforces for me the idea that a few seminary makeup courses -- or in fact a few more years in seminary -- aren't enough to make an ex-Presbyterian into a fully believing Catholic. It requires a real change in world view, and I respect people like Hahn and Campbell who seem to have felt that a Presbyterian vocation did not automatically transfer to a Catholic one.
The ordinations the other day of yet more second-tier OCSP candidates brought this back into focus for me. Fr Bayles, for instance, went to a Reformed seminary, and he's made his mediocre career on a Protestant denominational carousel. How much of any doctrinal changes have any ex-Reformed OCSP priests taken seriously, especially if they've already had a history of trimming doctrinal sails for one or another Protestant denomination?