Casus belli?
Are there any such thing as "innocent Muslims"?
What is your major malfunction? If all Muslims were as dangerous as you claim, the ENTIRE world would be rubble RIGHT NOW. As you can see, it's not. There are 1.5 billion Muslims in the world. Don't you think that if every single one of them was equally dangerous, we'd all be dead at this moment? Use you head.
Secondly, you need to understand that the Sunnis-Shia divide is as stark as the Protestant-Catholic divide was (and still is in many cases). For sure, the Sunnis are more old-school and the Shia are more easy going. The Sunnis are like the Catholics and the Shia are like the Protestants. Think of it this way: why do Iran and Saudi Arabia hate each other so much? Why do you think Saudia Arabia wants the West to attack Iran? Because the Iranians are Shia and the Saudis are Sunnis. That is a huge division within Islam.
There are also other offshoots of Islam, like Sufism and the Ahmadayia. And certainly, there are dangerous Muslims in the World that we need to target and bring to justice, or better yet, destroy, like the Jihadis, Salafis, Wahabbis and other Islamic terrorists. They are a minority within Islam and they need to be destroyed. That cannot be denied. But to blame the rest of the Muslim world for the actions would as absurd as blaming the entire Christian community for the actions of the so-called "Christian" KKK or so-called "Christian" Neo-nazis.
One thing I think you and I can agree on is that our common enemy is the terrorists. You need to realize that the Muslims' enemy is also the terrorists. If we write off a 1.5 billion Muslims, we would be discarding allies in the war against terrorism. That's undeniably true.