Support WBURWhy Islam Is The World's Fastest-Growing ReligionPlay05:12Download AudioJuly 17, 2017 ShareTurkish Muslims offer Eid al-Fitr prayers at the city's landmark Sultan Ahmed Mosque, or Blue Mosque, in Istanbul, early Sunday, June 25, 2017. Eid al-Fitr marks the end of the Muslims' holy fasting month of Ramadan. (Emrah Gurel/AP)