I've been told not to 'go back under the yoke of bondage' as St. Paul taught the Galatians, meaning that I should not re-enter Catholicism because it is 'another gospel'. This has worked well, and I found myself reading Galatians daily to maintain my zeal. I'm reading a book by a Reformed theologian named Fesko about the History and summary of the doctrine of justification, understood to be the gospel in Protestantism.
It seems to me that the argument of Alister McGrath about Augustine is wrong for a few reasons. The argument goes that St. Augustine didn't understand Greek or Hebrew, and only used Latin to write his theology and commentaries, and when it came to the Psalms the Latin was terrible in it's blatant mistranslations. Likewise the Greek word logozomai which should have been understood as a forensic/legal term for impute/recount/repute/declare something as just, was translated into Latin as iustificare which means 'to make just'. Thus St. Augustine and all the Catholic expositers on justification to Trent and beyond, shared in this mistake, and thus conflated justification and sanctification into one process of salvation, whereas they should've kept these two processes distinct like the human and divine natures of Christ.
...However the Eastern Orthodox who worked in the original Greek, and presumably had no such iustificare translations, also interpret Scripture in this way, and see justification, sanctification, and glorification (Theosis) as all one indistinguishable process. Looks like it's back to the drawing board there.