The Qur'an is very clear about it's denigration of Kaffir. For Christ's sake, the whole reason in pretending the Qur'an is a "Perfect" Book is to contrast it with and denigrate the "flawed" Kaffir's belief system (who by definition can't have a Perfect Book as that would remove the need FOR a Perfect book and thus a need for a protagonist named Mohammad). Simply put, there is no need for bigoted terms like Kaffir. I get by perfectly fine in life without ever using, thinking or coming across terms like Goy, Heretic, Infidel or Kaffir. In superstitious systems (where there are multiple Gods and Goddesses) such religious bigotry becomes moot. Anyway, it's a matter of thinking correctly - not that there's anything you could say to convince the Suicide Bomber. They have way too much invested in being a Suicide Bomber. Which, as SAM pointed out, is why they similarly have no faith in God.