However, I will say this. When the Turks arrived in Anatolia in the 1100s, there were only 25,000 Seljuks. So, obviously, a whole swath of the populace living in the region was converted. This population was not necessarily Christian either.

The initial invasions were actually quite brutal and consisted of forced conversions. Once in power, the Ottomans were more open to different religions. Of course, there were a few caveats. A Muslim paid less taxes and was allowed to own more property. Also, Muslims didn't have to give up their first-born males. The Janissaries were mostly Christian children. Nonetheless, other religions enjoyed a great deal of autonomy.

In the nineteenth and early twentieth centuries, you had many Muslims who spoke no Turkish at all. They only spoke Greek, Albanian or Slavic languages. It takes very little imagination to presume that they had been converted. Also, you had Turkish speakers who spoke no other language but were Christian. These were the Karamans. So, we don't necessarily HAVE to associate Turkey with a religion. The Ottomans were actually quite able to separate one's religious identity from an ethnic identity.

Only with nationalism, forced migrations and ethnic cleansing have the countries of the former Ottoman Empire come to seem so monolithic.