You probably don’t get it because your only concern is what is happening to Christian Iraqis with either true or willful ignorance of what is actually going on there. Guess what, those same atrocities that have/are being taken against Christian Iraqis have/are also being taken against all Iraqis. Your particular tribe/sub-tribe/family group determines who considers you and, for immoral individuals, who you consider a “marked man,” not your particular faith.
Iraq isn’t like the US where you might happen to know your grandmother’s maiden name, most likely have cousins who are of a different faith, and don’t figure out a person’s social/economic standing based on their extended family’s name (there isn’t even an equivalent to tribe in our social naming norms). If you want to “get it” about Iraq, you first need to figure out how Iraqi society/social interaction works. Iraqi Hatfield isn’t being attacked/killed by Iraqi McCoy because Iraqi Hatfield is a Christian (or Sunni or Shia); Iraqi Hatfield is being attacked/killed because he is an Iraqi Hatfield.
During the height of the sectarian violence in '06-'07 when Sunnis and Shiites were blowing up each other’s Mosques and killing each other we had an African Shia living in a Sunni neighborhood. He was able to live there and not worry about his safety (well anymore than the average Iraqi had to worry about his safety) because he, unlike native Iraqi Shiites, didn’t have any tribal “baggage” to worry about.