“The last crumbs of secular scientific education have been removed,” said Feray Aytekin Aydogan, the head of Egitim-Sen, a union of secular-minded teachers. Ms. Aydogan also scoffed at the suggestion that evolution was too complex a concept for teenagers to understand.
“Forget high school, you can comfortably explain it in preschool,” she said in a telephone interview. “This is one of the basic topics you need to understand living beings, life and nature.”
Over the past five years, analysts have noted how Mr. Erdogan’s government has steadily increased references to Islam in the curriculum and removed some references to the ideas of Mustafa Kemal Ataturk, Turkey’s founder. It has also increased the number of religious schools, known as imam hatip schools, and spoken of Mr. Erdogan’s desire to raise “a pious generation” of young Turks.
Mr. Erdogan has also moved gradually to reduce restrictions on the wearing of Islamic dress. In 2011, he removed a ban on head scarves in universities, and in 2013, scrapped a similar ban in the civil service. This year, he did the same for women in the army, an institution previously regarded as the last bastion of hard-line secularism.
For some, these changes simply constitute a progressive attempt to open up public space and discourse to the pious sections of the population that for decades were marginalized by the country’s secular and military elite.
“It’s not true that Turkey is becoming less secular,” said Ezgi Yagmur Kucuk, 20, a trainee anesthetist who does not wear a veil. “Everyone can believe whatever they like.”
Others, however, see an attempt not just to promote freedom of religion, but to ensure its primacy. According to Kerem Oktem, the author of “Angry Nation,” a history of contemporary Turkey, the country is “not continuing along a process of secularization — it’s going into a post-secular context.”
Still, Turkey is not considered likely to morph into a second Iran. The country’s vexed relationship with secularism also predates Mr. Erdogan’s tenure.
Technically, mosque and state were never completely separated in Turkey, even during the days of Ataturk. Instead, religion was placed under the control of the state. The process of legitimizing Islamic thought was in part begun during the rule of Kenan Evren, the army general who took power in a coup in 1980 and who viewed Islam as a potential buffer against communism.
To add to the complexity, Mr. Erdogan’s party — the Justice and Development Party, or A.K.P. — has a confusing relationship with Islamism, or the belief in a society governed according to Islamic law. It does not call for the application of Shariah law.
Its leaders have historically denied they are Islamists, preferring instead to be known as conservatives. Unlike the political wing of Egypt’s Muslim Brotherhood, a group to which the A.K.P. has sometimes been compared, several of its female lawmakers are unveiled.
One of Mr. Erdogan’s best-known supporters, Cem Kucuk, an outspoken commentator, has even called for hard-line Islamists to be expelled from the party.
The A.K.P. “uses religion to get votes,” said Jenny White, an expert on the changing role of Islam and secularism within Turkey. “But they do not have a coherent theological, religious ideology.”
The party and Turkish politics in general are best viewed through an authoritarian lens rather than an Islamist one, said Ms. White, the author of “Muslim Nationalism and the New Turks,” a book about identity in contemporary Turkey.
“The A.K.P. is all about staying in power — and whatever it has to do to stay in power, it will do,” she said.
Any further attempts to “Islamize” Turkish society is likely to be met with resistance, Mr. Oktem said. Despite Mr. Erdogan’s increasing authoritarianism, roughly half the country still voted against plans to give him more power in a recent referendum.
“Most of these people are those who don’t think religion should have such a central place in society,” Mr. Oktem said.
He added, “Turkey is still not a deeply Islamic society, and much of the public visibility of Islam doesn’t necessarily have a very deep basis.”
But for Ms. Aydogan, the teachers’ union leader, the outlook for secularism in the education sector is already bleak.
Removing evolution from the curriculum, Ms. Aydogan said, puts Turkey in the same league as ultraconservative Saudi Arabia, where the concept is briefly mentioned in the curriculum but strongly criticized.