(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.
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 idea of Western powers interfering with the historical unity of Russians and Ukrainians.
Three days after Russia invaded Ukraine, Kirill said in a speech: "We must not let dark and hostile external forces laugh at us, we must do everything to maintain peace between our peoples and at the same time protect our common historical Fatherland from all outside actions that can destroy this unity."
Smolkin says Kirill's rhetoric aims to show that the division between Ukrainians and Russians has been sown from the outside.
She characterizes the patriarch's Russian nationalist theory as this: "If Ukrainians think they are a different people from the Russians, it is only because they have been led astray by the West which has sown discord between these harmonious siblings."
In 2016, after the invasion of Crimea, a monument to Vladimir was erected in the middle of Moscow. Prior to that, the other major monument to Vladimir, erected in 1888, was in the center of Kyiv.
Kirill likely also supports Putin's war because he has recently lost power over several Ukrainian Orthodox Churches.
The Ukrainian Orthodox Church has had special historical ties to the Russian Orthodox church for centuries, a relationship which set it apart from other independent Orthodox churches, such as those in Georgia, Cyprus, Greece, Romania and others that form part of Eastern Orthodox Christianity.
In 2018, following the invasion of Crimea, part of the Ukrainian Orthodox Church severed ties from the Russian Orthodox Church, an act which raised the ire of the Russian Patriarch.
"For Patriarch Kirill," said Michels, "this is a matter of life and death."
Since the start of the war in Ukraine, there are even more signs of growing discontent within the wider Orthodox ranks.
The Russian Orthodox Church in Amsterdam announced on Sunday that it was severing ties with Kirill and the Moscow Patriarchate due to the latter's stance on the war.
"This decision is extremely painful and difficult for all concerned," the Amsterdam church of Saint Nicholas of Myra wrote on its website.
Some 300 Orthodox priests and deacons, including many who live and work in Russia, also risked disobedience to their leader and their country by publicly signing a letter calling for an immediate ceasefire.
"The Church is not a communist party that only speaks through its leader," said Russian Orthodox priest Father Andrey Kordochkin, dean of the Cathedral of Saint Mary Magdalene in Madrid, and a signatory to the letter.
Kordochkin noted that the letter mentions the word "war" four times; a word which is now illegal to print in Russia media.
"It is an act of bravery," he said, "especially for those who are physically in Russia, because we have families and are very vulnerable."
"I am inspired by Russian exiles of the 20th century," Kordochkin added. "I'm on a good list."
The governing body of bishops of the Ukrainian Orthodox Church, which is still connected to the Moscow Patriarchate, has appealed to Kirill to call on the Russian government to stop the war.
"Your Holiness! We ask you ... to call on the leadership of the Russian Federation to immediately stop hostilities that are already threatening to turn into a world war," the bishops wrote in an open letter on February 28.
Another Ukrainian Orthodox leader, Metropolitan Epiphanius, whose church is independent from Moscow, had even stronger words.
"The spirit of the Antichrist operates in the leader of Russia," he wrote in a February 27 statement. "This was Hitler during World War II. This is what Putin has become today."
In a significant act of distancing themselves from Kirill, 12 Russian Orthodox dioceses in Ukraine have removed his name from their prayers during the Divine Liturgy, on instruction from their bishops.
Pope Francis has so far refrained from calling on Kirill to condemn the war, and has not publicly condemned Putin or Russia by name, despite his fervent appeals for an end to the war.
Other Catholic Church officials, however, are not so reticent.
The Vatican's secretary of state, Cardinal Pietro Parolin, quickly distanced the Catholic Church from Patriarch Kirill's sermon demonizing gay pride parades, saying they risked "exacerbating" the situation.
The president of the Polish Catholic Bishops' Conference, Archbishop Stanislaw Gadecki, penned a letter directly to Kirill, writing on March 2: "I ask you, Brother, to appeal to Vladimir Putin to stop the senseless warfare against the Ukrainian people."
He also asked Kirill to urge Russian soldiers to reject their orders, saying that "refusing to follow orders in such a situation is a moral obligation."
Father Antonio Spadaro SJ, a close advisor to Francis and editor of the semi-official Vatican and Jesuit journal "La Civilta Cattolica" gave voice to what many in the Catholic and Orthodox world are wondering right now.
"The question of all questions is, what is Patriarch Kirill doing and what will he do?" Spadaro said in an interview with Italian news agency Adnkronos last week.
That question, given Kirill's statements so far, seems to have been amply answered.