What is the importance of the letter "J" in the book, J: A Novel?

J is the tenth letter in the modern English alphabet. It forms an important symbol in the novel wherein anytime a word beginning with a J is spoken, Kevern’s father holds two fingers across his lips. While the exact explanation of the two fingers is not given, the motion is obviously the code for “Jew.” As such, J with two fingers either symbolizes efforts to hide, distance, or pretend to condemn Jews and anything even associated with them, such as the letter J. This demonstrates the severe danger that Jews are facing.