oy. I dread topics like this simply because of people's misconceptions about Islam.
yes, the act of what was done is barbaric. yes, the Saudi regime is brutal and oppressive. However, you cannot take the actions and inhumanity of the Saudi Arabian regime and brand it "Islam". Even so, the Saudi branding of Islam is a strict Wahabbist Sunni brand, a very specific type of radical Islam.
Let's also not forget that the number one sponsor of Saudi Arabia is the United States, (which also is the number one sponsor of Uganda and their kill-homosexuals proposal), closely followed the UK.
In fact, Saudi Arabia was created by the British ("Lawrence of Arabia"), following World War I, when the British then gave a mandate to the Ibn Saud family to create a kingdom under their family in Arabia, thus naming it after the family patriarch, Saudi Arabia. Since World War II, the United States has taken over the spot of the British as the primary sponsors of the Saudis.
It's neither fair nor accurate to brand Islam as "backwards", "barbaric", or "uncivilized". These are Orientalist assumptions, and are routed in colonial discourse and racist theories. Orientalism serves as a justification for imperialism; since you describe a people or culture as the "Other", barbaric, backwards, uncivilized, you can thus justify your presence in their countries as a "civilizing mission", a humanitarian endeavour, or "war for freedom". This has been the case regarding western discourse of places like the Middle East and Africa for over 200 years.
Islam is in reality subject to so much variety, a plethora of sub-sects, different views, practices, beliefs, that to make any such statement as "Islam is extreme" is beyond ignorant.
Also, it shows ignorance to the growth of extremist Islam in the region and the world. This was not something that sprung organically from madrassas and Islamic communities; it's growth was entirely linked to the Western strategy in the region. In the 1960s and going into the 1970s, various nations were attempting largely socialist projects of governance. Afghanistan had an extremely progressive government in the 1970s; they had a democratic government, women were in government, they could drive, they were being educated, the people were by and large in favour of the government and its reforms. However, there were tribal leaders in the country who were opposed to this. The United States changed its strategy in the late 70s, to that of supporting radical Islamic groups.
Afghanistan, being a rather socialist government, had close ties to the Soviet Union, so naturally it became an enemy of the United States. So the US, with its allies in Britain, Saudi Arabia, and Pakistan, heavily funded, armed, and trained the Afghan tribal leaders into warlords, which began fighting against the Afghan government. The Soviets intervened, and then the Afghan-Soviet war was underway from 1979-1989. The CIA, working with British, Saudi and Pakistani intelligence, armed, trained and funded 100,000 radical mujahideen fighters between 1986-1992.
The Soviets withdrew in 1989 as the USSR collapsed. Subsequently, a new group emerged in Afghanistan, known as the Taliban. The CIA, working through Pakistani intelligence - the Inter Services Intelligence (ISI), created, funded, and armed the Taliban until 2001, when they again changed their mind about who should be in power in Afghanistan. Around the same time the Taliban were rising up, a pseudo-organization known as al-Qaeda began to emerge. Al-Qaeda actually means "the database", referring to the list of CIA and British intelligence assets used and created during the Afghan-Soviet war.
Covert US assistance for al-Qaeda lasted into the 1990s, such as the training of radicals at the alkifah center in Brooklyn. During the break up of Yugoslavia, US intelligence agencies, working with other western intelligence agencies (such as those of Britain and Germany), were covertly supporting the Bosnian Muslims, and later the Kosovar Albanians against Serbia. To do this, they brought in their intelligence assets from "Al-Qaeda" (the "database"), and funded terrorists to aid in the succession of these countries from Yugoslavia. Osama bin Laden was even involved in this process.
Even today, the CIA funds an al-Qaeda organization which is orchestrating terrorist attacks inside of Iran. The groups name is Jundullah, and it is run by a former high-level al-Qaeda asset.
The routes of radical Islam and the barbarism of events like 9/11, rest more on the shoulders of covert western imperial strategies than in the substance of Islam. These practices are a perversion of Islam. So perhaps before going and blaming "Islam", one should maybe look into what it is they are really trying to seek blame for.
Using words such as "barbaric", "backwards", and "uncivilized", only harks back to old imperial rhetoric and is grounded in racist, Orientalist assumptions which have been widely discredited. Besides, how "civilized" are our western nations who made it their goal to foster, finance, arm, and aid the spread of radical Islam, who wage war on the poorest countries in the world, who deny countries in famine the ability to grow food, who declare an election in a foreign country to be "fraud" and a coup in a foreign country to be "democracy"; how civilized are we in the way our nations act in the world?
If this is a contest of morality, barbarism, and humanity... we lose every time.