It is all too easy to forget here in west that there are extremely different versions of Islam in existence. Most of all there are also very different Islamic countries. In the other end of the spectrum is naturally Turkey, where the state and religion have been quite totally separated. The status of the Islamic religion was eroded in Turkey quite systematically for decades since the 1920’s and Kemal Ataturk.
Turkey has mainly for just this reason been for a long time a real success story among the Islamic countries. It is a showcase for a development where also Islamic religion can be pushed to its rightful place as a private matter only. These achievements are now under attack from the new Turkish Islamic parties, but the final outcome is still unclear. There are still good grounds to hope that the Turkish secular state will withstand even this newest attack.

On the other end of the spectrum there is naturally Iran, which has strong roots in the age-old and proud Persian culture and all of its achievements.
Like Turkey, Iran is historically, politically and ethnically quite separated from the Arabic Islamic world. However, it has ended up in the extreme opposite direction in its development than Turkey.

Turkey was never part of the original Arabic Islamic empire, as its modern area was mostly held by the East Rome or Byzantium as long as the original Arabic expansion lasted. The Islamization of the modern area of Turkey began only with the drifting of recently converted Turkish tribes to the former lands of Byzantium in the 11th and 12th century.
These tribes were the seeds of the Islamic Ottoman Empire, which slowly ate away the neighboring Byzantine Empire. Finally in the year 1453 they conquered also the Byzantine capital of Constantinople. These conquests did ultimately lead to the full Islamization of the area of the modern Turkey.

However, the Ottomans were great admirers of the Byzantine empire, whose neighbors they had been for centuries. They often did act as carriers of its traditions. Ottomans did also humiliate the proud Arabs by conquering almost all of the Islamic Arab areas in the Middle East.
The area of the modern Turkey has, in fact, never experienced the Arabization that was going on the other areas of the Middle East. This process of relentless Arabization has been going unabated for over a millennium and half in the lands that were conquered by the original followers of Mohammed in the 7th and the 8th century. This area consists of modern Jordan, Palestine, Lebanon, Syria Iraq, Egypt, Libya, Tunisia, Algeria or Morocco.

The Sultan Ahmed Mosque in Istanbul - Wikipedia

The wild Arab conquerors soon started a quite extraordinary program of cultural imperialism. These conquering Arabs did at first live as a parasitic ruling class in the vast and mostly Christian areas they had just conquered. The situation changed as Islam gained with time the majority position in these lands. After that there was a quite extraordinary phase of extinction of the original cultures and languages in these conquered lands.
The main weapon of this cultural imperialism was that the Arabic rulers allowed the reading of the new Holy Book only in the original language of the conquerors. In the end, this demand alone was a major reason for the extinction and near disappearance of many local languages and traditions. This was quite inevitable when the whole educational system in the Muslim world was based on the reading of this book and its interpretations.

The whole schooling system was soon uniformly based on this use of the language of the new rulers. This language was immediately also taken to be the chosen language in affairs the state. Very soon this system left no room for the old local languages and cultures. This development was of course intensified by the fact that you could not get to be a member of the ruling elite without mastering Arabic.
The majority of inhabitants of Syria, Iraq, Egypt, Algeria or Morocco are not really ethnical Arabs. They are descendants of people who have just in the past changed their language to Arabic. This language was forced on them by the new Arabic ruling class.

However, this fact of history is almost completely forgotten, as the Islamic religious movements do not want to dwell in this sorry history of their past conquests. The outside world so easily sees the Islamic world to be a one monolithic structure, which it really never has been.
When one remembers this, it is easier to understand why Turkey and Iran have traveled their so markedly different paths than the Arabic Islamic world.

Both of these countries do have a proud history of their own. Both do still have strong and living languages and cultures of their own. In fact, the bloody Islamic Arab invasion is not really remembered very fondly in Iran.
On this background, it is very easy to understand why the Shi’a Islam variety of Islam gained the following and eventually the majority position in just Iran, even if its basic teachings do not differ so wildly form the mostly Arabic Sunni Islam.
The greatest single difference is in the position of the Islamic clerics, who have much a much stronger standing in the Shi’a tradition. The other big difference is in the concepts of longing for the End of the World and cult of death so prevalent in Shi’a Islam, but almost completely missing from the Sunni version of this religion.

However, the very basic reason why this version of Islam did gain the upper hand in Iran is its open opposition to the mainstream and predominantly Arabic Sunni Islam. After the fall of original Arab Caliphate some of the new rulers in the former Persian areas sought eagerly for a way to draw their lands apart from the neighboring Arab Sunni rulers. They found a handy tool in the Shia Islam. A historic fact is that the first Persian Islamic rulers did promote Shi’a faith extremely heavily in Iran.

This difference in religion saved the age old Persian language and culture from extinction. One should not forget how the Arab Islamic culture swallowed many local cultures in the lands that the Arabic conquerors had acquired in the 7th and 8th century.
The Persian culture was naturally greatly transformed by the new religion, but it did survive and, in fact, a real life united front of Turkey, Iran and Arabic Islamic world is in fact nowadays nothing but a pipe dream.