The Magisterium and Scripture work together
Seeing the magisterium has only defined a handful of scriptures, one must assume that Catholics think all the teachings they give are infallible
I think the main problem you have here is that you don’t understand how Catholic teaching works. You see a little bit here and a little bit there, and you compare that with how things work in your denomination and think Catholics are doing it wrong. Which is ok, except when you then criticize Catholics based on a misunderstanding.
For example, we can explain some things from Scripture and some things from Tradition (for example, as shown in ECF teaching) and some things from Magisterial teaching. There’s a **lot** of overlap, as there should be, but sometimes one is clearer than another.
Because we have more sources of information, I get the impression that you think we somehow denigrate Scripture. We don’t at all; we just see that not everything is in Scripture.
As an example, consider the history of the idea of the Trinity, which is not explicitly explained in the Bible. Someone completely unacquainted with any Christian ideas would not read the Bible and see the Trinity in there. Where did that idea come from?
**Seeing the magisterium has only defined a handful of scriptures**
Not correct information
“Seeing the magisterium has only defined a handful of scriptures, one must assume that Catholics think all the teachings they give are infallible”
1) Who is “they”?
2) The number of verses defined - all of which are defined according to the prohibition of a negative sense rather than an exclusive sense - has nothing in itself to do with “Catholics think all the teachings they give are infallible”.
Are you sure you actually understand what you’re attacking?