Here’s the argument for inaction: you say “until they are stopped they will do everything in their power to bring our world crashing down around us” but how can they? What power do they possess to bring our world crashing down?
Muslims killing other Muslims, Arabs killing other Arabs; this is nothing new. It has been happening since Mohammad himself roamed this earth. Just because a new faction with an unusual form and an unusual brutality has arisen from the chaos of Syria and expanded into Iraq does not mean that it will soon be arriving on our shores. Indeed, there are many reasons to suspect that ISIS will contain itself to Iraq and Syria and perhaps Lebanon. The fighters who have brought ISIS such success are mostly displaced and disaffected Iraqis or Syrians who want merely to carve out for themselves a homeland in their old homelands, but this time under their preferred rulers and under a puritanical Islam—a kind of perverse democracy not of the ballot box but of the cartridge box. While such fighters may express a universal, proselytizing hatred of all things not 100% Mohammedan Muslim (except of course their ubiquitous Western designed, Asian built computers and their Toyota pickup trucks and their AK-47 copies designed by an Atheistic Soviet), just how committed will they be to fighting and dying to subject foreign lands to the will of Allah? Sure, if I were a country in that region, I’d be pretty nervous, but just how capable and how committed is ISIS to taking the Jihad beyond the immediate confines of the Middle East?
Many will talk about climbing Mt Everest someday, but how many ever even check the price of a ticket to Nepal? ISIS may puff itself up as a new generation of Islamic warrior intent on re-conquering and re-purifying the Arab world and then perhaps the world as a whole, but how committed is its leadership to the idea, and how willing would the foot-soldiers be to fight and die for such a cause?
Besides, it’s one thing for ISIS to spawn, mature, and hone itself in the chaos of the Syrian Civil War and then use that experience against such a place as Iraq, where the population was divided, the military poorly motivated and poorly led, and where the international “community” was distracted, indifferent, and fatigued. It would be another thing entirely for ISIS to try its hand against a target like Saudi Arabia or Turkey, a united country which has its shit together and powerful friends.
ISIS could destabilize the Middle East and provoke a general war between Sunnis and Shias, yes, but it could equally unite the Middle East as never before simply because ISIS represents such a threat to just about everyone and because it is so loathsome.
ISIS is a horror, no doubt, and will likely be remembered as one of the most horrifying features of the 21st century. But if they merely carve out a chunk of territory and rule it as they see fit, so what? Keep an eye on them, certainly, but getting involved will only risk our further entanglement in the perpetual quagmire of the Middle East and will almost certainly create more problems than they solve. It may well be that the only American victims claimed by ISIS will be the ones sent to the Middle East by our own government. Even if the specter of a virulent wave of Radical Islam spreading throughout the globe looms on the horizon, surely there are more effective and subtler means of combating it than sending legions of Americans to die?
Perhaps the best thing would be something from the pages of the history books. In the past, as recently as the Spanish Civil War, legions of volunteers from many countries would form and then fight on behalf of a particular cause. I am sure that throughout the world there are many Christians, Muslims, Jews, Hindus, Buddhists, Atheists and whomever else who see ISIS for the monster it is and would be willing to fight them on the battlefield to stop ISIS’ march away from civilization towards barbarity. Private funds could provide food, weapons, transport, could buy whatever training was not provided by the scores of veterans without a cause. It seems unlikely and perhaps a little naïve and idealistic to think that in this world dominated by the self-importance of governments that a group of citizens voluntarily banding together and operating beyond the scope of government could achieve any great effect, but it may be the only way to stand against this latest force of evil while also sparing our nation from adding any further entries to its long catalog of misguided foreign forays.