It has pretty much always teetered on the edge of that. I was stationed there for a year and a half, in 1967-8 while in the USAF. Religious tolerance was in the laws there, but was honored mostly in the breach of that tolerance, even then. There were Christian Churches in the city of Samsun, near my base, but they were sparsely attended. Islam was everywhere, since most Turks were Muslims.
The tolerance was barely practiced, frankly, even then, although lip service was given it. Today, with the increasing rise of purely Islamic states, Turkey has slipped even farther away from actual tolerance. This story contains no surprises for me. Even at universities in Turkey, Islam has a strong upper hand, and atheism is generally best kept to oneself.
While I was there, I formed a number of acquaintances, all of whom assumed I was a Christian, since I was an American. I did not make my atheism known, generally, because while Christianity might be tolerated by educated Turks, atheism was distinctly not tolerated.
That teacher was very brave to have spoken out in support of atheism and other religions. Sadly, he is now out of a job.
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