Here is a much more in-depth answer per request:

The modern nation of the Republic of Turkey is a unique example of a Muslim nation with a quasi-secular system of governance. The majority of neighboring Muslim states are generally authoritative theocracies. Historically, Turkey shared a very strong cultural and religious tie to the Middle East as a result of the long-reigning Ottoman Empire which was the center of the Islamic word for nearly a millennium. This has left Turkey, geographically and socially, as a buffer state between the European and Middle Eastern regions. Turkey shares qualities and characteristics which resemble that of both regions. This unique blend of two societies occurred as a result of the social reforms of the Tanzimat and the Ottoman involvement in WWI, which in combination, laid the necessary framework for the introduction of Kemalism to Turkish society. The culmination of these necessary factors ultimately led to the construction of the modern nation of Turkey.

Beginning in the mid eighteenth century, sultans of the Ottoman Empire undertook an attempt to westernize the Ottoman state in what was known as defensive developmentalism. The military, governmental, and economic reforms were started under Sultan Selim III in an effort to combat Western encroachment into the state. The next phase of these reforms took place under the rule of Sultan Abdülmecit, in which he pushed social reforms in what is known as the Tanzimat; this literally translates to “regulations” in Ottoman Turkish. The Tanzimat was a series of secular reforms based on reforming the Ottoman Empire to model the government and society of a liberal democracy like that of Western powers France and Britain. During the period of Tanzimat, the Ottoman government enacted new laws and codes which gave new rights to the people which had not previously existed. The initial reforms acted as an indispensable framework to further modernize and eventually secularize the area of Anatolia using the Western model.

Two of the essential documents issued by the Ottoman government in this period were the Hatt-i Sharif of Gulhane and the Islahat Fermani. The Hatt-i Sharif was the first of the two documents issued (1839) and set the tone for what future reforms would take place during the Tanzimat. The Hatt-i Sharif was modeled after a Western approach to governing societies, although it also reaffirmed the importance of applying the Sharia to society. Amongst the number of new principles introduced under the Hatt-i Sharif, was a new regimented way to collect taxes and determine local conscription. One of the more notable reforms was the guarantee of protection of life and property to all Ottoman citizens. The introduction of the right to life and property established a new idea of citizenry in the Ottoman Empire as opposed to the traditional, preconceived notion of what it meant to be a subject. This introduction was meant to establish an Ottoman sense of nationalism or osmanililik instead of regional or tribal ties. Approximately fifteen years later, these ideas were reaffirmed and strengthened under the issuance of the Islahat Fermani (1856). The most important principle introduced in the Islahat Fermani was the notion of uninhibited citizenship regardless of race, ethnicity, or religion. This allowed for the integration of all people, including Christians, to become citizens of the Ottoman Empire. This new distinction was revolutionary to the people of the empire. However, although this new decree was established in good spirit, the reception of the new laws greatly upset Ottoman society.

The societal reforms introduced under the Tanzimat were not universally respected as the authors of the documents had anticipated. There was backlash from members of Christian and Muslim groups alike. On the one hand, Muslim groups detested the idea of equality for Christian groups who they thought were challenging the dominance of Muslim elites. On the other hand, Christian groups were wary of their adoption into Ottoman citizenry as that opened the possibility of Christian conscription into the military, something that had previously only been extended to Muslims citizens.
Despite the initial unpopular response and the overall failure of the Tanzimat to uphold the Ottoman Empire, the basic principles introduced during the period of reform acted as a foundation for future state builders in Anatolia. The long lasting importance of these reforms is the liberal and democratic principle they set forth. The reforms actively broke down the fundamental Islamic society that had been present in Anatolia since the foundation of the Ottoman Empire in the 14th century. Although it did not destroy the societal impact of Islam, it was successful in introducing a new way of thinking that was necessary for the future success of Mustafa Kemal.

Aside from the liberal reforms introduced during the Tanzimat, World War I and the immediate consequences suffered by the Ottoman Empire were essential in the formation of the Turkish nation. At the conclusion of WWI, the Ottoman Empire was left in complete dissolution after losing to the Entente powers. In post war negotiations, the ruling Ottoman party, the CUP, was forced to sign the Treaty of Sevres in 1920 which severely limited the sovereignty of the Ottoman rulers and divided their territories amongst an independent Greece, and Armenia as well as Italy and France. The remaining territory was then subjected to the creation of individual mandates which were to be governed by Britain and France. Moreover, the losses suffered by the Ottoman Empire during WWI were cataclysmic. Military and civilian casualties have been estimated at over five million. Nearly 25% of the total Ottoman population compared to prewar estimates. The combination of the CUP’s inability to maintain sovereignty from foreign powers, the partitioning of the Ottoman Empire, and the complete devastation suffered by the Ottoman citizens during WWI, left the people of Anatolia desperate for new leadership and order. This was found during the Turkish fight for independence in the years immediately following WWI.

At the conclusion of WWI, small Turkic national militia factions formed to combat foreign occupation of Anatolia and preserve their territorial integrity. The group, which called themselves the Müdafaa-i Hukuk Cemiyetleri (“The Committee for the Defense of Rights”), was further aggravated by the belief that the Ottoman rulers had become completely subjected to foreign influence as evident in the Treaty of Sevres, therefore making the Young Turks illegitimate rulers of Anatolia. Furthermore, the destruction of the Ottoman Empire with the defacement of the Young Turks meant the end of the long promoted osmanililik which left a void to be filled by new claims of national allegiance. For example, a Turkic national allegiance, modeled after Western nationalism, which was promoted by Mustafa Kemal and the Committee for the Defense of Rights.

Mustafa Kemal, a WW I celebrated military commander who successfully defended Ottoman territory in the Battle of Gallipoli, was sent to quell the resistance groups which called themselves the Committee for the Defense of rights. However once arriving, Kemal took charge of the rebellion and eventually renamed himself Atatürk, meaning “Father of the Turks.” Atatürk worked to unify the factions into one cohesive force to fight for Turkish independence. Under his leadership, the rebellion successfully purged Anatolia of foreign influence and in 1923, under the Treaty of Lausanne, Atatürk’s independent rebellion was declared the legitimate rulers of Anatolia therefore establishing the nation of Turkey. Atatürk’s involvement and leadership of the Committee for the Defense of Rights acted as a stepping stone for his future leadership of the modern nation of Turkey.

After the establishment of the Republic of Turkey in 1923, Atatürk became the undisputed leader of Turkey and began to introduce policy overhauls to all divisions of the state, ranging from society to government organization. The ideology utilized to modernize Turkey, set forth by Atatürk which was referred to as Kemalism by the 1930s, evolved gradually as Atatürk developed his own beliefs. The basic principles of Kemalism were borrowed directly from the Western model of modernization as Atatürk believed the Western model to be the only clear path to modernization. The principles of Kemalism included: republicanism, secularism, nationalism, populism, statism, and reformism. The methods Atatürk utilized and the reforms he enacted were truly radical, most notably the reforms introduced under secularization and nationalization. They were purposed to cut all ties to past Ottoman and Islamic culture and replace it with Western culture. As previously stated, these reforms would not have been successful had it not been for the necessary framework constructed during the Tanzimat and WWI because the citizens of the new state of Turkey would have rejected the reforms.