Protestants believe that the Bible is the sole highest and final authority in all matters of belief and practice.
Roman Catholic apologists reply with, "Ah - but you Protestants, with your Bible alone, don't agree with each other! You need something more!" That something more is the supposedly-infallible Roman Catholic church.
In a clear and concise post here, James Swan shows that this shift in reality achieves nothing. The same Roman Catholic apologists then disagree with each other on how to interpret the pronouncements of that supposedly-infallible church.
The fact that people disagree over the Bible's meaning shows nothing. People disagree over everything, and when those people are sinners handling a book that strikes right at the heart of sin, it's hardly surprising. There's no mileage in scoring apologetic points from that observation on its own.