When you are at gun or sword point and told convert to islam or die, that's when you will understand. OR when you lay dying in a sky scraper after a bunch of muslims flew a plane into it because they hate the country you happen to be in, then you will understand.
oh and to save you the googling,
in·fi·del
/ˈinfəd(ə
l,ˈinfəˌdel/
derogatory•archaic
noun
noun: infidel; plural noun: infidels; plural noun: the infidel
a person who does not believe in religion or who adheres to a religion other than one's own.
"a crusade against infidels and heretics"
