Paul only wrote half the letters attributed to him, John didn't write John, Mark didn't write Mark, Matthew didn't write Matthew, and Luke didn't write Luke. Of the 27 books of the NT only 8 are attributed correctly.
As for their supposed dying for their faith we don't actually know that. That is all later church traditions. It's certainly possible since pretty much everyone got murdered who the Romans noticed but we don't have evidence that it happened to them and there was plenty of reason to lie about it.