It was a speech "heralding the liberation of the full Muslim world," Prodromou said.
The speech rooted Turkey's "sovereign right" to reconvert Hagia Sophia in its Islamic past, and aims to "justify what he [Erdogan] sees as a kind of religious destiny, and also a geopolitical model for Turkey's revisionism and expansionism."
Erdogan is "trying to fuse Islam and Turkish nationalism in a way that energizes those two twin bases," she said of his political ambitions, and thus it carries serious implications for religious freedom, equal treatment under the law for religious minorities, and respect for cultural heritage in Turkey.
Christian minorities in particular could be affected by such a change in policy. Turkey's population is overwhelmingly Sunni Muslim, with Catholics, Orthodox Christians, and other Christian denominations making up only a tiny fraction of the population. There are 2,000 or fewer Greek Orthodox Christians left in the entire country, Prodromou said.
Erdogan's speech, she said, "is a clear signal, in particular, to the Ecumenical Patriarchate of Constantinople," as well as "a signal beyond them" to other religious minorities, "that this is about Sunni Islamic dominance and hegemony in Turkey."
It also aims "to promote division" between Christians and Muslims "that need not exist," she said.
And the goals outlined in Erdogan's speech could impact not just Turkey, but the broader region of the Middle East as well.
In his July 10 speech, Turkish leader predicted that Hagia Sophia's reconversion would herald the liberation of al-Aqsa mosque on the Temple Mount in the old city of Jerusalem, the third-holiest site in Islam.
Erdogan views Turkey as the mosque's "protector," Prodroou said, as well as the protector of "all Muslims who seek to go and pray there."
Given Turkey's history of violating the sovereignty of its neighbors such as Iraq, Iraqi Kurdistan, Northern Syria, and Cyprus, she said, "this is a declaration that Turkey will do as it wishes" in the wider region and even beyond the region "where it sees its sovereignty rights, even where those are completely at odds with international law."
"It's also a powerful rejection of the Kemalist understanding of secularism, which ultimately was about control of religion," she said of the previous secular government that had converted Hagia Sophia into a museum.
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Hagia Sophia will become a mosque on July 24-a date which is "rife with symbolism," Prodromou said. It's the anniversary of the Treaty of Lausanne, signed in 1923 after the defeat of the Ottoman Empire in World War I, which established the borders of the modern Turkish state and included explicit protections for Christian minorities there.
"He [Erdogan] has stated indirectly-and increasingly, directly-that he sees Lausanne as something that should be abrogated," Prodromou said. It's also a signal to Turkey's NATO allies and fellow countries that it "is not interested in continuing within the context of treaties that are meant to provide stability and order in the region."