"..After the Christians left Mosul, the Islamic State
marked Christian homes and businesses with the
letter N for Nazarene. The terrorists told local
business owners not to serve Christians or they could
be punished with death. It did not take long for people
to put "We are all Christians" next to the letter N on
the homes..."
http://www.breitbart.com/national-security/2014/07/28/resistance-grows-against-islamic-state-in-iraq/