The Russian Orthodox church is the remnant that survived the 70 years of communist hell. It is integrated into the FSB and plays a significant part of forming Russian foreign policy.
Russia is on a crusade to rechristianize the Balkans, the Caucuses and to prevent NATO from enforcing the secular/moslem new world order on Russia.
As NATO encircles Russia and adds military buildup around the edges of Russia - the more determined are the Orthodox to protect their sheep and they have nukes and cash.
After the USA becomes a balkanized mess, Russia will look like the last man standing.
The Moscow Patriarchate is the remnant of the thoroughly subverted Communist/KGB church, not the heroic underground one.