We are commanded to test all things. We are also told that God's word is a lamp to our feet and a light to our path. We must, therefore, test the teachings of, e.g., the so-called Magisterium, against the Bible. If they differ, or if the Magisterium pronounces teachings not found in the Bible, then those teachings must be discarded.
This was one of the pillars of that great, God-given deliverance from darkness known as "The Reformation": a return to the word of God and a departure from the traditions and superstitions of men. This, along with justification by faith in Jesus Christ, instead of absolution supposedly being doled out by sinful priests, is absolutely vital. Of course, many other things are also vital; but, lacking the unchanging, objective standard of the Holy Bible, against which to test all things, and lacking justification by faith in Jesus Christ alone, marks out Roman Catholicism as a false religion, not Christianity.