Just to reiterate something I saw on Twitter. (Speaking of the aftermath).
"Much depends on there being a difference between Islam and Islamism, wherever it doesn't exist, we must create it."
I think that's pretty accurate. The two are often conflated (and that's not necessarily a hugely difficult thing to do - meaning it is relatively easy to arrive at such conclusions), but the difference is that one is a religion (all encompassing all kinds of people), and the other is the desire to impose Islam over society. In the case of ISIS, their Islamist objective also follows an ideological path - away from the political side of things. The ideology of Salafism/Wahabism (sp?), Saudi Arabia is also a Wahabi state.
ISIS' are using militant jihadism to execute that objective. The Muslim Brotherhood, as I understand it - used democracy to make the change they sought... To give a juxtaposing method.
In fact, one of their stated goals is the fulfillment of prophesy, as I understand it, that the Sunni Islamic armies will engage with the armies of the West in a final battle... (The place name escapes me, I think it began with a 'D')
Pretty scary stuff when you think of it. The terrorism seeks only to goad the West into further military intervention (which some might say is inevitable - I'm on the fence) thereby fulfilling said prophesy.
You can't bomb the ideology out of existence... Just as Nazism still exists today (and we bombed the sh*t out of Hitler!) - it is, however, wildly unpopular - the same thing must happen with the Islamist ideology (whether by natural progression out of theocracy in countries in which theocratic, authoritarianism rules), or by Western intervention. Though I think a true eradication, or de-popularisation of Islamism must come from within the faith and the region - lest it be seen as Western imperialism.