That is what is happening, now, in areas ISIS has taken over in Iraq.
Among others, children are getting executed with their entire families, for not converting to Islam, and then getting their heads removed and impaled on sticks placed in towns to warn of what happens to those who do not embrace the "religion of peace". Apparently 500 women and girls have been taken by ISIS, as rape booty, but I doubt most Western feminists will demand anything be done about that, they'll be worried that there aren't enough women in the board rooms of banks.
That's why it is morally right for the US, indeed for any military force that wishes, to eradicate ISIS.
The Western allies that overthrew Saddam Hussein owe it to Iraq to step in, over the heads of the weak sectarian Shi'a government, and use air power to curtail ISIS, then to fund and arm new Iraqi armed forces, consisting of Shi'a, moderate Sunni and those from other backgrounds, to eradicate this menace.
Meanwhile, the anti-Western, anti-capitalist Amnesty International demands Israel faces an arms embargo, for defending itself against the only part of the Palestinian territories that is attacking it.
Meanwhile, the tens of thousands of supporters of Gaza, march give moral approval to aggressive Islamism, albeit that comparing Hamas to ISIS is like comparing the Green Party to the Khmer Rouge.
If ISIS is not contained and takes control of sufficient oil and gas fields to fund endeavours elsewhere, make no mistake the price of appeasement will be high.
So ISIS must be kicked out of Iraq and, in spite of all that he is, a deal must be struck with Bashar Assad and the secular Syrian opposition, to do the same in Syria in exchange for a truce between Assad and the opposition as a prelude to a federal settlement, elections and his standing down as President.
and to the appeasing peaceniks who oppose?
Your intellectual forebears would have had us in a communist one-party state, and before that would have demanded peace with Hitler. You are not defenders of freedom or civilisation, but appeasers to barbarity, dictatorship and slavery.
This is a battle between civilisation and barbarity.
Barbarity that is disowned by Iran (primarily for sectarian reasons), but also disowned by Al Qaeda itself.
There can be no compromise with such evil. There wasn't with the Nazis or with militarist Japan.
That is the moral clarity behind the fight. It should be NATO, it should be Arab allies, it should even be Russia, China and India in support (for both dictatorships are themselves threatened by the brethren of ISIS).
However, assuming that little is done, watch and see the world that isolationism brings.
PS: I was going to write a piece critiquing the Green transport of people in cities policy, but that's not remotely important.