Patriarch Kirill heads to Poland this week for a historic fence-mending visit, the first by a head of the Russian Orthodox Church since the country regained independence after World War I.
During his four-day visit, from August 16-19, Kirill is scheduled to meet with leaders of the country's Autocephalous Orthodox Church, tour some of its churches, and hold talks with top officials and leaders of Poland's Catholic Church.
But the highlight of his visit will be the signing of a document calling on Poles and Russians to forgive each other the dark pages of their shared history.
The document will be signed by Kirill and Archbishop Jozef Michalik, the head of Poland's conference of bishops, on August 17 in Warsaw's Royal Castle.
"We are deeply convinced that relations between the peoples of Russia and Poland, which have often been marred by hatred, wars and enmity, can and must be improved," said the Russian Orthodox Church's head of external relations, Metropolitan Hilarion, ahead of Kirill's trip.
The appeal is the first of its kind to be penned by the two churches. Like the Moscow Patriarchate, the Roman Catholic Church in Poland has carefully stressed that its message is solely spiritual, not political.
Jozef Kloch, a spokesman for the Roman Catholic Church in Poland, said that in this joint message, "history is mentioned only in general terms, because it's mostly the job of historians to deal with history."
"But it's very important to pave the way for dialogue, to engage in discussions based on the evangel of Jesus Christ common to both our churches. The goal is also the reconciliation between people, ordinary people," Kloch said.
Russia and Poland have been historical foes and enemies on the battlefield for centuries and nurse deep mutual grievances. In recent decades, a number of episodes have clouded relations between the two countries.
Poland continues to seek justice for the Katyn massacre, in which more than 20,000 Polish officers were executed by the Soviet secret police in 1940. Poles resent Moscow's subsequent decades of domination in the postwar era, which only ended in 1989.
Russia, in turn, accuses Poles of mistreating Red Army prisoners in the 1920s. More recently, Poland angered Russia in 2008 by accepting to host elements of a planned U.S. antimissile shield.
Warsaw and Moscow have also traded barbs over the 2010 plane crash that killed Polish President Lech Kaczynski and 95 others and over the issue of alleged proselytizing by the Roman Catholic Church in Russia.
Russian religion analyst Mark Smirnov says Kirill's reconciliation efforts are partly due to the change of leadership within the Moscow Patriarchate following the death of Patriarch Aleksii in 2008.
"The Russian Orthodox Church's head of external relations, Metropolitan Hilarion of Volokolamsk, once served in Lithuania and enjoys close relations with the leaders of the Catholic Church in Poland, with the head of Poland's Catholic Church, and he has been there a number of times," Smirnov said. "He is behind such initiatives to seek reconciliation between peoples through inter-church dialogue."
In another recent gesture toward Poland, Kirill made a pilgrimage last month to the burial site of Katyn massacre victims, in Russia's Smolensk region.
But the Russian Orthodox Church is known for its close ties with the Kremlin, and Kirill's visit is widely seen as having political undertones, too.
"Behind all this stands a policy authorized by the Russian Foreign Ministry. This way, Moscow is signaling that it would like to find compromises. Russia is worried that Poland will become a NATO base, especially regarding antimissile defense plans," Smirnov said. "So this is obviously also an attempt to influence Polish politics and the Polish public."
Patriarch Kirill's landmark visit to Poland could also be overshadowed by the controversy surrounding the all-female punk dissident band Pussy Riot, three of whose members are on trial for singing a song critical of Vladimir Putin and the Russian Orthodox Church in Moscow's largest cathedral.
A Moscow court is due to hand down its verdict against the trio on August 17, the day Kirill signs the Russian-Polish reconciliation appeal.
The Moscow Patriarchate has been criticized for its unforgiving stance against the three women, who face up to seven years in prison.