As a non-religious person it pains me that instruction in religion is still required to understand many present day world events. When I say non-religious - I mean that I do not subscribe to what is known as institutional or organized religion.
Many beliefs so fanatically pursued today by devoted adherents bear little to no resemblance to the goodness or opinions that inspired them in the first instance and say more about human weakness, geopolitics, ambition, greed and intolerance than spirituality.
Evolution & Interpretation of Islam
Over the last thousand years Islam has spread through various groups spread and hundreds of ethnicities and in the process has evolved very differently in different locations.
The Indian sub-continent has a greater Muslim population than all the nations of the Arabian peninsula put together. With Indonesia, Pakistan, Nigeria, Iran and Bangladesh in the mix then the the Arabs become a very small minority among Muslims worldwide.
Many Muslims (especially ones outside the Arabian peninsula) have adopted some elements of the surrounding culture and their traditions from pre-Islamic practice and look very different to the beliefs at the root of most of the trouble at the moment.
Islam is not Monolithic
Islam does not have a monolithic structure and is rather made up of many different sects. These sects vary widely in their interpretations of Hadith (Islamic customs), have varying internal structures, follow different worship patterns and have different attitudes to externals and other religions and belief systems.
For example the the Sufi school of thought is more tolerant of other religions a trait shared by the Ibadiyyas while the Saudi Hanbali sect is conservative and Wahhabi/Salafist movement is downright fascist in its views. Persian Muslims identify more as Persians than Muslims. The Shafi'i muslims of Southeast Asia and the Kurds of Turkey, Syria, Iran and Iraq are moderate in their interpretation of Sharia. Sufism is prevalent in Southeast Asia but this also giving way to a more extreme Deobandi movement that has inspired the rise of Taliban. There are also a few very moderate schools like Ahmadiyya and Mahdavia a lot of it influenced by Indian cultural elements.
Almost every major religion has a conservative segment that interprets the religious edicts more seriously than the mainstream. Sometimes these extreme sects also get quite violent. Even the highly pacifist Buddhist religion went on a rampage against the minorities in Sri Lanka and Burma/Myanmar.
Tolerance and peaceful co-existence is the worldview of the majority of Muslims and the radical sects represent a very small but highly visible percentage of the total. It is the saturation coverage in the mainstream media of radical Islamism, much of it without context, that represents one of the greatest dangers we face in terms of marginalizing Islamic moderates in Western society.
Much of what is going on in Syria, Iraq, Afghanistan and North Africa at present has its roots in the actions of external groups and interfering foreign interest groups.
Monarchies & Dictatorships
Many successful Muslim countries - Indonesia, Turkey and Malaysia are democracies. The majority of Muslims in these countries are moderate given the level of social stability although this has changed significantly in Turkey over recent years. Historically though the Arab world has in the main been defined by monarchies or dictatorships promoting a tendency towards extremism in the population manifested in 2011 in the Arab Spring which kicked off events in Syria and Libya.
The 2004 BBC television documentary series by Adam Curtis called The Power of Nightmares explains the evolution and escalation of the current conflict over time and the external influences and politics that motivated many of the actions that have the region where it is today.
The Middle East is of course a very strategic region and thus a number of external players have always operated there out of self-interest preventing democracy and in many cases supporting tyranny. The Saudi regime is supported by the Americans who have also fomented sectarian conflict in Iraq by supporting the anti-Sunni government some years ago. Over the last 50 years Russia, France and Great Britain have all sought to overtly and covertly influence events in the region.
The Many Forms of Extremism
Salafi is the most extreme Islamic school of thought (Sayyid Qutb) and is the biggest source of terror groups funded by Saudi oil money. They are ~1% of the world Muslim population, but are responsible for a big chunk of the trouble. Al Qaeda and ISIS are both Salafi groups.
The Taliban is a Afghan Pashtun organization based on the Deobandi school of thought. The Muslim Brotherhood and Hamas in the Gaza Strip are Sunni. Hezbollah is a Shia organization. The civil wars in Syria and Iraq have exposed the radical sectarian tendencies within Islamism and the Saudi-Iranian proxy conflict in Yemen has showcased the fact that much of the funding and motivation for the sectarian conflict in the region has its roots in these two countries as they compete for regional influence.
Controlling the Ummah
Conservative extremists have not agreed on how they should remove the non-Islamic influences and even what is counted as non-Islamic. Many of the extreme groups believe their own interpretation of the Quran (religion), Hadith (customs), Sharia (law) is correct and that the other schools of thought are deluded or even demonic. And they go to extreme lengths to prove the other one is incorrect. Fundamentally, it is all about power. Each ethnicity and each school of thought wants to be the one that controls the Ummah.