To a Protestant who was under the impression that we Catholics consider the Catechism as more authoritative than the Bible, I pointed out that the Catechism has the authority the Church’s Magisterium lends to it. The Bible alike is authoritative only because the Catholic Tradition and Magisterium guarantee it is a faithful and inspired report of Revelation*. The Catechism is, in a systematic and technical way, a faithful report of all the important teachings of the living Tradition. Each phrase, and almost each word in it, like any other authoritative document of the Church, has many bearings in the Tradition and the Bible, as can be checked in the numerous references.
Most Protestants, it seems, practically equate the Word of God with the Bible, as if the divine Revelation was only present to us in Scripture. But it is not so: the Word of God is a real living bodily** Person, who promised to stay with us through a living organism that he entrusted with his Revelation.
The Bible is not historically prior to Tradition, nor has doctrinal precedence on it; the Old Testament was produced by the Jewish Tradition, the New Testament by the Catholic Church Tradition. As the Bible is all about Christ, His Bride the Church inherited the Jewish Tradition and the Jewish Bible from Him. Then the Torah and Prophets (Hebrew Scripture), as well as the Greek Old Testament, is hers, too.