Strategy Page looks at the various forces and factions opposed to the rise of the Caliphate of ISIS:
In the Middle East Islamic radicalism, and its murderous offshoot Islamic terrorism, comes in many different flavors. Most groups are mutually antagonistic and will often kill each other as eagerly as they go after kaffirs (non-Moslems.) Nearly all these radical movements now condemn ISIL (al Qaeda in Iraq and the Levant) and condemn ISIL for being too extreme. To the West these seems absurd, and many Moslems agree. But radical Islam is what Islam began as and to this day there are always Moslems who embrace the concept of extreme Islamic radicalism and Islamic terrorism as being the ultimate form of Islam. Thus while Saudi Arabia bans all other religions in its territories and regularly beheads people accused of sorcery and other religious offenses, the Saudis condemn ISIL. One reason for this is that ISIL considers the Saudi government weak and not Islamic enough and worthy of being replaced (after a righteous bloodbath of the current Saudi royal family) by someone more suitable (like ISIL). Al Qaeda also condemns ISIL, initially for not ignoring al Qaeda orders to tone down the barbaric treatment (mass murder and torture) of the enemy because al Qaeda realized that this eventually triggers a backlash from other Moslems. Iran condemns ISIL because all Shia (meaning all Iranians) are heretics and deserving of summary execution. Iran-backed Hezbollah is now using that ISIL threat to justify Hezbollah grabbing more power in Lebanon, where Shia are a third of the population but far more powerful politically because Iranian cash, weapons and training have made Hezbollah too strong for the elected Lebanese government to suppress or even oppose. In Syria, the minority (more Shia) Assad government, fighting a Sunni rebellion since 2011, now calls on their current Sunni enemies (Saudi Arabia and other Gulf Arabs, plus the Sunni majority in Syria) to join with them in destroying ISIL.
Whatever else ISIL has done it has united many other Sunni faction and the Shia in the region into an uneasy anti-ISIL coalition. But even after ISIL is gone, Islamic radicalism will still be there. For most Moslems this radicalism is like the weather; every Moslem talks about but Moslems cannot seem to do anything to eliminate or even control it.
Islamic terrorism has long been trapped in a self-destructive cycle of its own making. It works like this. Islamic radicals obtain their popularity and power by proclaiming that they are defending Islam from non-believers and sinners (within Islam, often local Moslem dictators). In order to maintain this moral superiority, the Islamic radicals must be better Moslems, and insist that others do as they do. Since Islam is a religion that dictates how one lives, in considerable detail, as well as how one plays, this business of being a “good Moslem” can get tricky. And it is. There’s a race underway by Islamic radicals, and the clergy that provide theological support, to issue, and enforce, more and more rules on how a good Moslem should live.