Now that I have answered your question, please be so kind to answer mine: Since Jesus and the thief on the cross were not Catholic, and the Bible does not say anything about being a Catholic, why would it be necessary for any Christian to be a Catholic?
until Christ died for our sins....we were under the old covenant
Catholic of course means universal as opposed to Jewish which was tribal. Later it came to be used as a way to distinguish one denomination from another. The Bible does not use monotheistic or Trinity but I would argue that those concepts are implicit in the text. Nowhere in the Bible does it say “Scripture alone” but that certainly did not stop many Protestants from subscribing to that notion.