(CNN)Russian President Vladimir Putin has given several explanations for his country's war on Ukraine, and some are more plausible than others. They include stopping NATO's advance towards Russia's borders, protecting fellow Russians from "genocide" or the baseless claim of "de-Nazifying" Ukraine.
In Putin's vision for the world, a medieval narrative resurfaces
The top-ranking priest in the Russian Orthodox Church, meanwhile, has offered a very different reason for the invasion: gay pride parades.
Patriarch Kirill said last week that the conflict is an extension of a fundamental culture clash between the wider Russian world and Western liberal values, exemplified by expressions of gay pride.
Yet experts say that Kirill's comments offer important insights into Putin's larger spiritual vision of a return to a Russian Empire, in which the Orthodox religion plays a pivotal role.
The hardline stance of the Russian patriarch is also costing him followers, however. The Russian Orthodox church in Amsterdam announced on Sunday it was severing ties with the leader, just the latest in number of priests and churches who are abandoning Moscow over the war in Ukraine.
"Putin has been putting forward this concept of the so-called Russian World and that concept is grounded in Russian Orthodoxy," Victoria Smolkin, associate professor of history at Wesleyan University, told CNN.
"The Russian World is wherever there are Russian speakers, the Russian World is wherever there is a Russian church -- it does not acknowledge existing political borders," Smolkin said.
Putin's vision is supported by Kirill, who also sees Ukraine as an integral, historical part of his Russian church, Georg Michels, professor of history at University of California Riverside, told CNN.
"At the beginning of the war, Patriarch Kirill gave a sermon in which he emphasized the God-given unity of Ukraine and Russia," said Michels in a UC Riverside News interview.
"Kirill denounced the 'evil forces' in Ukraine that are out to destroy this unity," Michels explained.
Last Sunday, Kirill went a step further during a sermon in Moscow when he specifically linked these "evil forces" to gay pride events.
According to the patriarch, the war in Ukraine is about "a fundamental rejection of the so-called values that are offered today by those who claim world power" -- that is, the West.
The "test" of which side you are on, said Kirill, is whether your country is willing to hold gay pride parades.
"In order to enter the club of those countries, it is necessary to hold a gay pride parade. Not to make a political statement, 'we are with you,' not to sign any agreements, but to hold a gay parade," he said during the March 6 sermon.
"If we see violations of [God's] law, we will never put up with those who destroy this law, blurring the line between holiness and sin, and even more so with those who promote sin as an example or as one of the models of human behavior," Kirill said. "Around this topic today there is a real war," he added.
Kirill's speech denounced the infiltration of Western liberal values into the hearts and minds of what he said were the historically unified and Orthodox Ukrainian and Russian people.
"He's saying there is a civilizational clash and that the gay pride parades in this narrative is a litmus test for which side you're on," Smolkin said.
Despite calls for Kirill to denounce Putin's war, the "Russian Pope" has not only refused to do so, but instead has provided moral legitimacy for the invasion by calling it a struggle of "metaphysical significance," of humanity choosing to follow God's laws.
"The Russian Orthodox Church is providing much of the symbolism and ideology that Putin has used to cement his popularity," added Michels.
The city of Kyiv is highly symbolic for both Putin and Kirill because of its connection to Vladimir I, a medieval ruler of Kievan Rus' -- a territory which included parts of both current-day Ukraine and Russia -- who converted to Christianity in around 988.
"According to the now-dominant Russian nationalist view, Vladimir was the founding father of the first Russian state and the Russian Orthodox Church. State and church formed a productive symbiosis and Kiev (or Kyiv) became the cradle of Russian civilization," Michels wrote.
"Putin considers Vladimir the savior of Russia," Michels told CNN. "To him, Kyiv and Crimea, where Vladimir was baptized, are sacred Russian lands."
The Christianization of Kievan Rus' is the founding narrative upon which Putin and Kirill claim Ukraine as part of Russia.
"They're trying to wrest this legacy of Kievan Rus' for Russia and that's a really critical part of Putin's view of history and the role of Russian Orthodoxy in that history," said Smolkin.
"What Putin is claiming is that he is restoring the natural God-given order of things: that the Ukrainians and Russians have always been one people and they all know that because they all come from Kievan Rus' and they're all Orthodox."
Kirill's speeches have also reinforced this