Father Serpa writes: The Scripture that St. Paul writes about is the Old Testament because the New Tetament didn’t exist yet. So does your friend really want to say that the Old Testament is sufficient and nothing else is needed? I don’t think so.
St. Paul is saying that Scripture is inspired and useful. He is not saying that God only speaks to us through Scripture as your friend wants him to say. It is always, always necessary to know the context of whatever Scriputre passage one is considering.
I understand Father’s reasoning, but as a former Protestant, I know the counter argument would go something like this:
Even tho the New Testament did not exist as St Paul was writing his letter, he was being inspired by God to write it to be included in the New Testament for future generations. Therefore, God was telling us, the future generation, that all Scripture is indeed sufficient.
My point is that I don’t feel pointing out that St Paul was referring to the Old Testament when he spoke of Scripture would be convincing enough. The argument would come back that God himself was writing the letter thru St Paul to be included in the Bible, and so God was telling us that Scripture alone is sufficient.
Of course, I don’t by the argument, but how would we rebut this?