During the Reformation, one of the primary ssues was that of authority. And it is, indeed, the central issue that divides biblical Protestants from Catholics: by what standard do we judge truth? The Catholics answer with the Bible, church tradition, and the Magisterium, i. e., the church hierarchy. The Reformers answered with the Latin phrase, Sola Scriptura, Scripture alone. That does not mean that everything must be explicitly stated in the Bible, but rather that it must be either explicitly stated or necessarily logically required by it. In the words of the Westminster Confession of Faith I:6, "The whole counsel of God, concerning all things necessary for his own glory, man's salvation, faith, and life, is either expressly set down in Scripture, or by good and necessary consequence may be deduced from Scripture."
Protestants defend our position in various ways. An excellent one can be seen here, by the late Orthodox Presbyterian Rev. Greg Bahnsen. In response, Catholics ask the question, legitimately, if hypocritically, "Where does the Bible teach sola scriptura?" Again, various answers, some better, some worse, are given. I will offer one that I have not seen from anyone else.
"When they say to you, 'Inquire of the mediums and the necromancers who
chirp and mutter,' should not a people inquire of their God? Should they
inquire of the dead on behalf of the living? To the teaching and to the testimony! If they will not speak according to this word, it is because they have no dawn" (Isaiah 8:19-20). God, speaking here through the Prophet Isaiah, asks the very question I am addressing: how should the people of God judge truth and falsity? And He gives the only infallible answer: By comparing it to the Word that He had breathed out (II Timothy 3:16), i. e., the Bible.