Grace & Peace!
I think if we define “sola scriptura” as a belief in scripture as the only form of revelation, then it is certainly problematic, to say the least. However, if “sola scriptura” is understood as a belief that every doctrine necessary for salvation is contained in scripture, then I don’t know that I see so much of a problem. Are there doctrines necessary to salvation which the Roman Catholic Church holds that are not contained in scripture?
I think, though, that this argument is not about sola scriptura at all, irregardles of how it’s defined–it’s a question of authority. I’m an Anglo-Catholic. My church does not require me to believe in the Assumption of Our Lady, and does not define belief in it as necessary to salvation. I do not believe belief in the Assumption is necessary to salvation either. I do believe in the Assumption, however. The Assumption as an article of faith in itself may not be necessary to salvation to a Roman Catholic, either, but because a Roman Catholic is bound by their communion to believe the Assumption as it is defined by the Magesterium, not believing in it can be seen as a rejection of church teaching and therefore a de facto act of heresy calling their salvation into question. But what’s at issue here is not if the Assumption is attested to in either scripture or tradition, but whether or not the Magesterium says that a Roman Catholic must believe it.
So what’s really at stake here is neither the value of tradition nor that of scripture, nor the ability of either of them to reveal necessary doctrine, but the nature of the authority which validates that doctrine. And insofar as the reformed traditions do not subscribe to the authority of the Pope nor the Magesterium of the Roman communion, there will be differences of opinion between Roman Catholics and their reformed brethren.
Under the Mercy,
Mark
All is grace and mercy. Deo gratias!