I believe that Sunnis and Shias are all Muslims.
And that the problems we are having right now are just political.
Even though there's a lot of people think that it's natural for a country to do and say whatever is necessary to serve its own interests. I don't believe that is the right way to go. Since it's rare that our interests ever intersect, and we will always fall into the same trap.
In my opinion, any side that used religion or a "higher purpose" as the reason behind his actions, is only working for his self-interests, and is causing harm to Islam first, knowingly or unknowingly, and is making peace harder and harder to achieve between our peoples.
I believe both sides are at fault here for this crime.
There a lot of Sunnis who fell into the trap of demonizing the Shia public, justifying crimes against Shia because of their religious beliefs. I'm always rethinking my own beliefs and self criticize when I talk to some of these people. Who have no sense of the basic concepts of crime and punishment, and of the basics of humanity and lack the simplest tools of critical thinking.
Some of the people from both sides are just angry at the injustices that they suffered at the hands of the people that call themselves "Shias" or "Sunnis" regardless of how well they represent that school of thought. I'm sure many Shias protest against using their religious beliefs to further someone's political ambitions and goals.
Shias who were victims of sectarian terrorism causing them to adopt the belief of (we against the world), Sunnis suffering from unjust rulers and military dictators causing them to lash out at everything and anything that stands between them and what they believe is the perfect Islamic utopia.
It's just the human condition.
I mean for the sake of argument, let's say that their principle that Shias or Sunnis are not Muslims is right. In the Quran it clearly says don't insult their "Gods" so they don't insult yours. We are not supposed to insult the cows that the Hindus worship. So I believe if we're not supposed to insult that, then logically we shouldn't insult someone's religion, saints, beliefs, culture, etc etc.
Even I sometimes talk in that tone, so I apologize for that.