By Daren Butler and Humeyra Pamuk
ISTANBUL (Reuters) - Evoking the Ottoman conquest of Constantinople and vowing the Muslim call to prayer would forever ring out, President Tayyip Erdogan put religion centre stage on Saturday as campaigning for Turkey's parliamentary election entered its final week.
Persuading religious conservatives, including pious Kurds and nationalists, to back the Islamist-rooted AK Party will be key in an election Erdogan hopes will bring him stronger presidential powers that opponents see as a threat to democracy.
Turkey's most dominant politician for more than a decade and founder of the AK Party, Erdogan draws much of his support from the pious masses. His rhetoric often plays on a tension reaching back to the 1920s when Mustafa Kemal Ataturk forged a secular republic from the ruins of an Ottoman theocracy.
"We will not give way to those who speak out against our call to prayer," he said in a speech in Istanbul to mark the anniversary of the 1453 Islamic conquest that turned the capital of the Byzantine Empire into the seat of Ottoman power.
"We will not give space to those who want to extinguish the fire of conquest burning in the heart of Istanbul for 562 years," he told a sea of supporters waving the red Turkish flag, most of the women covered in the Islamic headscarf and some of the men wearing headbands bearing Erdogan's name.
An AK Party video released to commemorate the conquest culminated with the Muslim call to prayer being recited from a minaret of the Hagia Sophia, Christendom's greatest cathedral for 900 years until the Ottomans turned it into a mosque.
Ataturk, who banished Islam from state affairs and promoted Western dress and women's rights, decreed it a museum in 1934. But a burgeoning sense of Islamic identity that Erdogan has encouraged has revived interest in praying there.
"I don't mind if Erdogan uses Islam as a political propaganda tool. I actually appreciate that he brings it up. These are our values, we shouldn't forget them," said Ahmet Sahin, a 26-year old accountant among the crowd.
"LIES AND SLANDER"
Erdogan appeals to conservative Muslim Turks who feel they were treated as second-class citizens during decades of rule by secular parties. He has spoken with scorn of the old secular elite. "They drink their whisky on the Bosphorus ... and hold the rest of the people in contempt," he once said.
Constitutionally banned from party politics as head of state, Erdogan has nonetheless delivered podium speeches around the country in recent weeks ahead of the June 7 election, berating the opposition and arguing for a presidential system.
He wants the AKP to win a strong enough majority to change the constitution and hand him greater powers unopposed, something opinion polls suggest it will struggle to do.
Erdogan casts the main secularist opposition Republican People's Party (CHP), founded by Ataturk, as hostile to religion, but the biggest electoral threat is likely to come from the pro-Kurdish Peoples' Democratic Party (HDP).
If it crosses the 10 percent threshold needed to enter parliament it would steal seats from AKP, potentially leaving it unable to form a majority government.
Seeking to win over pious Kurds, Erdogan has devoted much time to questioning the HDP's Muslim credentials, describing them as followers of the Zoroastrian religion and accusing them of an insulting reference to the Kaaba, the most sacred site in Islam which worshippers face when praying.
"These people have nothing to do with Islam," Erdogan, who held aloft a Kurdish translation of the Koran earlier this month, told a rally in Istanbul this week. "I believe my pious Kurdish brothers will give them the necessary answer on June 7."
Islamist media accused HDP co-leader Selahattin Demirtas of eating pork, something he has denied.
"For weeks the president and prime minister are going around saying 'I am a Muslim' and running a campaign of lies and slander," he told CNN Turk on Wednesday.
"This is black propaganda designed to smear me in the eyes of a part of society."
Turkey's state-run religious affairs directorate has been caught up in the campaigning. The HDP has said it wants to abolish the body and remove state involvement in religion.
Defending the directorate, Erdogan insisted on providing its head with a luxury armoured car and a private airplane, saying he deserved the same treatment as other religious leaders, including the pope. Turkish media quoted a Vatican spokesman in response as denying the pope had a private jet.
"They have gone so overboard with exploiting religion in politics ... Instead of showing the pope as an example, why don't you take our Prophet's life as an example," said Kemal Kilicdaroglu, head of the opposition CHP.
(Writing by Daren Butler and Nick Tattersall; editing by Ralph Boulton)