According to the Times of India, in Syria and Iraq the ISIS Warriors (Sunnis) quiz captured Muslims to find out if they are the hated Shias with 4 questions:
4 questions ISIS rebels use to tell Sunni from Shia1. What is your name? A quick look at an Iraqi's national identity card or passport can be a signal. Shias believe that the leadership of Islam was passed down through the Prophet Muhammad's son-in-law Ali and his sons Hussain (or Hussein), Hassan and Abbas, among others. While some Sunnis and members of other Islamic groups may also have those names, ISIS would most likely associate them with the Shias.3. Where do you live? In every city and province, even majority Sunni ones, there are enclaves that are known to be Shia. People who said they came from one of those neighborhoods would most likely be killed.3. How do you pray? Shias and Sunnis offer prayers in slightly different ways, with Sunnis generally folding their hands or crossing their arms in front of their stomachs and Shias leaving them extended, palms resting on their thighs.
In a chilling video that appeared to have been made more than a year ago in the Anbar Province of Iraq, ISIS fighters stopped three truck drivers in the desert and asked them whether they were Sunnis or Shias. All three claimed to be Sunni. Then the questions got harder. They were asked how they performed each of the prayers: morning, midday and evening. The truck drivers disagreed on their methods, and all were shot.4. What kind of music do you listen to? Recordings of religious songs could also be a tipoff. Similarly, even the ringtone on a person's telephone could be a clue because it might be from a Sunni or Shia religious song.-more