Rhetorical: Korihor’s attack on the belief in Christ continues with an attack on the source of those beliefs. To completely understand Korihor we must reference the appearance of Abinadi before the Priests of Noah. Those priests professed a belief in the law of Moses, and the doctrine found on the brass plates, but they denied the coming of the Christ, the Atoning Messiah (see Mosiah 13:26-33). While Abinadi asserts that all of the prophets form Moses on taught of the coming Atoning Messiah (Mosiah 13:33-34) the Priests of Noah were nevertheless able to deny the Christ by denying what Abinadi thought clear.
The brass plates, of course, correspond to much of the Old Testament with which we are familiar. As with Abinadi, we may look with special knowledge on the past testament to understand the images that we may now understand as referencing the mortal mission of the Savior. However, it is also abundantly clear that the Jews were able to read those same passages and deny then, and deny now, their relationship to Jesus of Nazareth.
Korihor may or may not have a belief in the brass plates, but it is virtually certain that the prophets he is belittling are the Nephite “modern” prophets. Just as the Priest of Noah could hold their position only by denying the very clear teachings of the New World prophets, it is probable that Korihor similarly attacks the New World tradition of prophets rather than the Old World tradition. We see this in his designation of the prophecies as the “foolish tradition of your fathers.”
The “fathers” in the Book of Mormon nearly always refer to the New World lineages, not the Old World contexts. Korihor is laying the foundation of his doctrine by attacking the purely Nephite prophets, those who would not be supported by the sacred tradition of the brass plates and the Old World. In a very real sense, he parallels the modern world that denies the words of the modern prophets, dismissing all they have to say as part of our modern “foolish traditions.” Once again the proof Korihor uses that the Nephite prophets were wrong – even worse, foolish, is that no one can know of such future events.