Ok, then which side do you think is in our best interest to “support” for purely strategic reasons? Sunni or Shia?
If you’re going to use that WWII analogy it seems to me that we should be ‘supporting’ ISIS (Sunni) in the short term as Iran (Shia) is a more immediate threat and larger scale threat (nuclear).
In your analogy we team up with ISIS (Stalin) to get rid of the more immediate and dangerous threat of Iran (Hitler)? Then we deal with ISIS later?
ISIS can unify the Muslim world. It is hacking through great swathes of land without an air force, in the face of coalition air attacks. The Shiites are like Islam's Mormons. They will never be accepted as mainstream Muslims. Apart from Iran's nukes, Shiites are a nit (10%, at best of the world's Muslim population). Sunnis already have nukes (Pakistan), but no Sunni country has ever threatened to nuke Israel. What Obama needs to do is erase Iran's air force and institute a no-fly zone over the country that periodically rubbles any suspicious installations. But he won't do that because he's a dove. (GWB did not do it because he would have been impeached by Democratic majorities in both chambers). And that is why Iran will get its nukes.
Given Iran's inability to rein in ISIS, both in Iraq and Syria, I suspect even it, too, is vulnerable to conquest by ISIS. The long-term risk is that ISIS conquers Iran and Pakistan, thereby getting its long-sought nukes, in addition to the Gulf kingdoms, whose populations are far more radical than their current fun-loving moderate rulers (who make a show of public piety while drinking and whoring their way through the lands of the infidel), and therefore more than ready to join ISIS.