There were nearly three decades between the Crucifixion and the first books of the New Testament and nearly eight decades between the Crucifixion and the last of them. Two generations at least were deprived of the Book of Revelation, surely one of the most critical of the books of the Bible. Many Christians already had gone to their deaths for the sake of Christ, but had never heard the words of Paul, for the simple reason that Paul had not yet written them. Indeed, at least one Christian died as a direct and intended consequence of Paul himself: Stephen. Are we then to exclude Stephen from salvation because he was unaware of Paul’s writings not yet written?
All the teachings of the apostles are "traditional" teachings, not "written"—"Traditional" in the radical (root) sense of the term, from the Latin "tradere," to hand over (not "down" as so many have it—nor does the idea of "trade," also derived from that verb, enter into it implying some exchange of one sort or another), simply the passing along from one to another. The Bible is the written portion of Tradition, as is amply evidenced by John himself at the very end of his Gospel, where he says that "many other things did Jesus do and say, so many, I think, that if they were all written down the world itself would not be large enough to hold the books that would have to be written to hold them." Even taken in their most gentle sense, those words inescapably mean that in no way can the Bible be taken as the complete record of everything Jesus did, said, or taught.
Most of the beliefs and practices that Fundamentalists condemn among Catholics are rooted in Sacred Tradition, the unwritten portion; though I also must make certain that it is understood that no Tradition, however longstanding, may contradict Scripture.
Revelation is of a piece; it is not a patchwork quilt, from which we pick and choose those things that please us or which may threaten us less. Salvation and revelation are a package deal—they go together, and we accept all or none.