While some RCs affirm Scripture is infallible - incapable of teaching error or deceiving- because people misinterpret it - (like Catholicplanet.com), yet some deny that and criticize evangelicals for not having an assuredly infallible interpreter for their supreme material authority, and relying on fallible human understanding.
However, RCs also misinterpret their supreme authority, the magisterium, and which is not considered to be Divinely inspired, while their decision to submit to it is a fallible one.
In addition, as said, they cannot know even how many infallible decrees there are, while Rome’s plethora of pronouncements, lack of perspicuity, and variance of interpretation among the magisterial interpreters of the magisterium necessitate great reliance upon their own fallible human understanding.
Moreover, the assurance promised and attained in Scripture did not await an assuredly infallible magisterium of men, else no one could have assurance that the God of Israel was the true God, and test truth claims, before the church of Rome infallibly proclaimed herself to be so.
But souls could know based upon the Scripture and the power of God it affirms and was established by, with Scripture, once written, being abundantly evidenced to be the supreme transcendent standard or earth for obedience and testing truth claims.
Amen!
"But now is made manifest, and by the scriptures of the prophets, according to the commandment of the everlasting God, made known to all nations for the obedience of faith" (Romans 16:26)