It had nothing to do with non believers and martyrs, that's just recruitment rhetoric, I mean ol Osama has spelled it out in so many of those old VHS recordings for us:
"There is America, full of fear from its north to its south, from its west to its east. Thank God for that. What America is tasting now is something insignificant compared to what we have tasted for scores of years. Our nation [the Islamic world] has been tasting this humiliation and this degradation for more than 80 years. Its sons are killed, its blood is shed, its sanctuaries are attacked, and no one hears and no one heeds."
"The American people had risen against their government's war in Vietnam. They must do the same today. The American people should stop the massacre of Muslims by their government."
"Free men do not forfeit their security, contrary to Bush's claim that we hate freedom. If so, then let him explain to us why we don't strike Sweden, for example."
"I present a reconciliation initiative... whose essence is our commitment to stop operations against all (European) countries if they promise not to be aggressive towards Muslims or interfere in their affairs."