I can most certainly determine what was contained in scripture. The point was that Paul taught that we, like the Bereans, are not to take the word of man but to check with what was inspired by the Holy Spirit to be written as a benchmark for the voracity of what they taught. The RCC makes the claim that what they teach is not to be checked by scripture.
>>Asking the question, “what was written” raises the very next question - what exactly was written down that he’s referring to.<<
The inspired words of the Holy Spirit is what he was referring to. Not some myth perpetuated by some self serving organization. The inspired record which Jesus so often quoted which was preserved by God to counter the lies of Satan. We confront that same situation when debating with followers of the RCC.
“The RCC makes the claim that what they teach is not to be checked by scripture.”
Incorrect. His Church makes the claim that what it teaches is His Word.
“The inspired words of the Holy Spirit is what he was referring to.”
How do you know the Gospels are the word of God? Why do you believe the New Testament is authentic? On what authority do you rely?