Crypto-Christians (or Klosti) have been present in Pontus (Black Sea region of Turkey) since 1650 and resulted from the fanaticism of certain Derebeys (valley lords). During this period, the Ottoman Empire parted into ‘Derebrelics', in other words, feuds or themas. The leaders in those areas, in many cases, showed exceedingly high fanaticism, and oppressed the Christian population, thus forcing them to convert to Islam. The early attempts towards the islamization of the Pontus Greek population first appeared in the Ofis region, followed by Surmena , Argyroupolis, Ionia and other regions.
In public, these Christians exhibited the typical appearance of a Muslim and took part in the usual Islamic rituals just as a genuine Muslim would. At the same time they could be found in places where undercover priests held liturgies and were present at all private gatherings associated with the Christian Orthodox faith.
The Crypto-Christians avoided arranged marriages to Muslims in many ways, thus allowing marriage between Christians to continue. This lasted until February of 1856, when pressure by the European powers on the Sultan, led the way to the signing of the "Hati-Humayum" which resulted in all Ottoman citizen being allowed the right to revert back to his or her original creed, in this case Christianity. This policy existed between 1856 and 1910, however the policy changed in 1910 with the arrival of the Neo-Turks and their implementation of a Panislamic policy. Until then, it was not unusual to see entire villages in Pontus revert to Christianity
2.The changes in the Muslim state and Crypto-Christians.
2.1. The Tanzimat
The period of great change in the Ottoman State "the Tanzimat  period" was initiated by the Sultan Abdul Medjit (1839-1861) and his Act, "The Hati Sherif" in the year 1839  which was ratified and later expanded to the Hati Humayim in 1856. This period is partly overlapped with the administration of Abdul Hamit B' (1876-1909). The consequence of these reforms affected the economy, with an increase in trade with Europe, a more intense penetration of Western business firms, and a re-organization of local agricultural produce with a hope for the Empire's survival, as well as political, economic and social effects particularly with regard to the non-Muslim population. Thus the most serious repercussions of the reforms was the future of social development. Greek-Turkish relations were therefore directly connected with the existence of Crypto-Christians within the Ottoman Empire.
2.2. Hati Sheriff.
The creation of the Hati Sheriff, which Minister of Foreign Affairs and six times Grand Vizier Moustaffa Ressit Pasha greatly contributed to, was co-ordinated in such a way that would satisfy both the conservative Muslims as well as the liberals. The table of privileges that was issued on 21 October / 3 November 1839 contained the following points of privileges;
- Warranty of life assurance, honesty and property on all subjects.
- Order on the fixing and revenue payments.
- Arrangement  of enlistment and military duties in general.
These privileges were to be enforced on the followers of any creed and in the same way, irrespective of formal religious beliefs,  but at the same time it made no explicit mention of equality amongst Muslims and non Muslims. The difference in taxation with the "haratsi" the capita impost and other rates and duties at times imposed, still went on for the former, with the exception of the "capita impost" when in May 1855 a case was brought forward for a compulsory military enrolment of all non-Muslim citizens of the empire. From one point of view they were considered a threat to the Muslims who believed that it was only them who had the right to carry arms or be armed, while at the same time the Christians were hoping that there would be a change in their up to then status of being able to exercise an exemption in military duty. Therefore this section of the reforms was not applied and the pre-existing conditions continued, with Christians having to pay a special tax for exemption.  This new act however was not widely accepted because the Muslim population reacted against the better welfare of the Christians, not only in a political sense but materialistically as well as economically as was evident by their communities in the capital city Constantinople and also in the big cities of the country like Andrianopolis, Smyrna, Caesarea or Ikonio.
Assassinations took place in 1840-1842 against Christians. Prominent citizens in certain areas quite often refused to abide by the reforms and as a result were forcibly islamized. In Caesarea three entire villages were forced to change their creed during that period and part of the above population chose crypto-Christianity thus preserving both creed and ancestry. Preservation of morals, traditions and cultural inheritance were some of the defence measures used during these peculiar and very painful times. In the year 1843 an Armenian of Constantinople, who had been forced into Islam, was given the ‘death penalty' upon reverting back to Christianity. The Ottoman authorities felt the pressure exerted on them by the European powers in relation to these reversions, but it did its best to evade this inviolable Muslim law of imposing the death penalty for those who apostated from Islam. 
2.3. Hati Humayun.
The Hati Humayun of 6/18 February 1856 was issued after pressure exerted by the European powers whose aim was the establishment of equal rights to the Christians of the Ottoman Empire. In this way they were also depriving the Russians of mixing with the affairs of the Ottoman state. By enforcing the Hati Humayun, all Christians obtained equal rights with Muslims in terms of religion but also legality. To this the Sultan emphatically said: "My heart makes no exception between the slave of my empire. Rights and privileges will equally be shared with no distinction to all with no exception". In towns and villages Greek- Christian schools were opened. Freedom to worship one's own religion was granted both inside and outside of the church which was one of the most important changes.  The Ottoman state ratified the National and General Regulations of the Patriarchy, which would become the Constitution chart of the Orthodox Church till 1923. Of great value was the opinion of German clergyman H. Gentzer on the Greek communities of Minor Asia for the period after 1836. "In Asia Minor the Greeks are making an unexpected progress. They grow in number quickly because there are a lot of children in every family. They move from place to place all the time. At first a grocer will migrate. Then some families will move there too. A teacher follows, a church is erected, a priest is elected and soon a new Greek community is set up".  The example of Amissos (Samsounta) is most characteristic. Until 1860 Amissos was only a small village of 4,000 inhabitants. But within 50 years it became the biggest and busiest port with a population of 40,000 people of which 2/3 of them were Greek. 
From 1856 until the official recognition of Cappadocia and Pontus Crypto-Christians by the authorities in 1911, there were several sources detailing the Crypto-Christians with the most characteristic being that of P.S. Sideropoulos (or Pehlil), who unveiled himself to his boss the Italian Consul Fabri. On May 14th, 1856 Sideropoulos was finally recognized as a Christian  by the Ottoman authorities. This was great news for all those who were still hiding their true faith, and on July 15th, 1857, 1590 Crypto-Christians congregated at the church of Theoskepastos in Trapezous, after a memorandum to the Sublime Port, the ambassadors of the European powers and the Ecumenical Patriarchy. 
A report of the British sub-consul A. Stevens in 1857 addressed to the British ambassador Stanford regarding the Kromni district in Pontus, stated that in 55 villages, 9,535 Muslims resided there, 17,260 Crypto-Christians and 28,960 Christian Greeks. Gervassios the Bishop of Sevastia made reference to the Crypto-Christians of Asia Minor by saying that, after European interventions there in the year 1858, 25,000 of them confessed publicly their Christian creed.  The return to Christianity by these Ottoman subjects frightened the authorities who followed the developments with great unease.
To hinder these changes, the names of Christians on official lists were altered with the addition of the words "Tenessour Roum" beside their names. This basically meant that he or she was an apostate or a denier of his or her creed. Christians who were labelled in this way had to undergo the corresponding added sufferings. Their children were not allowed to inherit their parents' properties. The proceedings were implemented with the aim of halting the trend of Christians returning to their former creed but also to safeguard domestic income. 
The period after 1869 is characterized by an increase of persecutions towards the Crypto-Christians. Some tried to gain Russian citizenship as a means of escaping this. In the year 1876 there were acts of violence in the Pontus region which persisted for many more years.
The reforms that took place in the Ottoman state came to a peak in 1876 together with the preparation of the New Constitution by the Great Visier Midhat Pasha, the head of the Neo-Turk movement. During this period, the Ottoman state took the shape of a Constitutional monarchy, but soon Abdul Hamit B' abolished the Parliament. It was only shortly before the Young Turk movement in 1908 that he was forced to proclaim the second constitution for a new parliament assembly on July 23rd 1908.
3. The 1876 Ottoman Constitution and the Crypto-Christians.
The constitution resulted in the equality of rights among all citizens to be declared for all religions and it was then that Crypto Christians of Cappadocia openly declared their creed. The Greek Stavriotes, who took their origin from the Stavroti village, led a double life for a great length of time, being Christian in private and Muslim in public. During the Easter of 1877, 300 Stavriote families were bold enough to publicly declare their Christian creed celebrating "Ressurection", in church thus taking advantage of the constitution. The 1876 constitution charter was no longer in use and formally, nothing changed in their district. People were able to send their children to Greek Orthodox schools, attend church and go to matrimonial ceremonies. Up until 1898 the Ottoman authorities took a soft approach towards these events, but after the 1897 Greco-Turkish War, wild persecutions broke out against Asia Minor christians, especially in the neighbouring Trapezus area. The Abdul Hamit "Kulturkampf" cultural battle, waving the Pan-Islamic flag, did not prove to be free of bloodshed. The Sultan put forth a plan towards an enforcement of Ottoman culture fomenting religious devotion to Islam. Studying in Greek schools was banned, children born by non recognized Christian parents were considered "bastards` and illegitimate, and on a grand scale military enlistment was carried out. 
4. Neo-Turks and the Crypto-Christian Question.
The Neo-Turk movement first appeared in the Ottoman political field with the issue of the magazines ‘The interpreter of Times' (Tercuman-I ahwal), and ‘Picture of Thoughts' (Tasvir-I- Efkar) with the basic aim of radically changing the operating structure of the Ottoman State.  In the first phase of development of the Young-Turk movement there were groups with differing objectives to that of the leading group, and the atmosphere in general was expressed by slogans and the general policy of a Pan-Islamic Ottomanism, Turkish nationalism and modernization. Very few of these groups thought that Christians and Muslims should have equal rights within a modern Muslim state. Some followers of a Pan-Islamic ideal advocated for the islamization by force of the Christian population and particularly the children, a movement which was met with the approval of those living in the remotest parts of the empire, and away from the urban districts where Christians were a minority.
The islamization problem developed into a serious one for the Patriarchy and the church in general, forcing its religious leadership to send out ecclesiastical reports (takriria) to the Ottoman State with the aim of discussing the particular problems.
The Neo-Turks appeared in the decade of 1870 with the so-called Modern Ottoman party, a party of liberals who owned big farm properties, and the small bourgeois class, which had just started to come into being. With the bankruptcy of the Ottoman State in 1875, the party, mobilizing the people, made the Sultan Abdul Hamit B' appoint the Great Visier Midhat Pasha, who despite wearing the mask of political liberalism and of rights, amalgamated the non Muslim citizens with Islamic and Turkish ideology. The Neo-Turks took shape with the establishment of their own club, "Unity and Progress" at the Military Medical Academy of Constantinople in 1889. But the climate of freedom of movement did not last long, and its leading hierarchy were persecuted and gathered close together around the ‘Committee' of Union and Progress in Paris (1897). The Union played an important role in its base.  As a result of the 1905 census, and around 1907 and the 1908 revolt, things again led to tension concerning the Crypto Christians and Stavriotes who were demanding to be registered as Christians, a request which was answered with acts of violence. 
The 1908 Neo-Turk revolution resulted in the Sultan restoring the parliament which he suspended 1878. It was something that was welcomed by Christian Greeks and other minorities and religions of the state. But they soon realized the chauvinistic character of the movement, as it was realised that they were now planning the extermination of the non Muslim inhabitants. It was a period characterized by a seeming retreat of the Ottoman administration on the relevant demands of Crypto Christian recognition. Through memoranda, Stavriotes attempted to bring their demands into action once again, but it took them at least 2 or 3 years before a tentative solution was given with the acceptance of the Neo-Turk side of the Crypto Christian problem. The Stavriotes insisted on being censured as Crypto-Christians. Although the Neo Turks spoke for reforms, they were practically chauvinists. Turkish was established as the official language. Up to secondary school, the language used was now solely Turkish. The right to become a Member of Parliament was only allowed to those who had good knowledge of the official language and their ‘Osmanism' was proclaimed as their national ideal. It was a way of practically denying the existence of other nationalities, and thus trying to assimilate them by force. The Young Turks' main aim was to build their rebellion around legal and constitutional frameworks in order to keep order all over the country, in this way crushing the fight of the working class and the national liberation movement of the non-Turk populations.
The French historians E. Dicault and M. Lheritier wrote that, "the modern Turkey of 1907 was more nationalistic rather than liberal. Ahmet Keza in the Young-Turk gazette adopted the right of self-control, but this right was claimed mostly by the Turks ...". The constitutional Ottoman Empire, for all its declarations, which affected people of various nationalities, simply continued the Sultan's policy. The reforms were neither materialized nor respect shown to its minorities.
At the Young Turk conference in Thessaloniki in 1911 decisions were adopted which turned against every non Muslim minority who lived within the boundaries of the Ottoman State. "Turkey should eventually become a Muslim country. The Mohammedan's concept and power should keep control throughout the country. Any other religious propaganda should be banned. The existence of the Empire depends on the forces and power of the Neo-Turk party and the crushing of any other ideology antagonizing it. The Muslimization of peoples should be completed as soon as possible. Of course, it is clear that it cannot be accomplished by convincing them and that the only way is to use armed force. The feature of the empire should remain Mohammedan and upon this we should see that Muslim laws and decrees will be respected by all. The right of all other nationalities to have their own organizations should be obliterated. Any form of decentralization or self administration will be considered treason for the Ottoman Empire. Nationalities are elements of no value. They may be allowed to keep their creed but not their language. Expanding the Turkish language is one of the most basic principles for securing the Mohammedan superiority and the assimilation of non Mohammedan populations".
The German ambassador in Athens A.Wangenheim wrote to the German Chancellor of State F. Bulow explaining to him what the Turk premier and Minister of Defence, field Marshal Sefrer Pasha, said about the new state of being "The Turks have taken up an extermination battle against the Christians of the empire. Turkey is going to be the starting point where the majority of them exists, and then outside Turkey, where there are centres of resistance".
Since the very beginning, the Neo-Turks tried to crush the Crypto-Christian turn over, and at the same time inflict a strong blow to the religious beliefs of the Greeks. Nazim Bey, one of the leading members of the movement said to the Greek poet Argyropoulos, "the Greek feeling must for the sake of the salvation of Turkey be diminished not only at school but also anywhere it comes up".  The Turk ambassador Ahmed Reza used to say about the Greeks of Asia Minor during the same period, "Modern Turkey wants to put an end with the confusion of these two nations, that is, the Greeks and Turks, because by the word Greek it means all Christians. He wants the Greeks to understand that the Greeks of Turkey are Turks not Greeks. The Ecumenical Patriarch should stop being the centre of Hellenism. The Ottomans who are the only masters of their home will surely impose their will on all the benevolent ones, and with the tolerant ones, but with a greater stability than ever before". This programme was brought into action with the outbreak of World War I, on all respects that dealt with the Christian nationalities of the Ottoman state, leading to an enormous rush of people islamicizing, long before the compulsory population exchange took place.