Greek nationalism was made possible by the Russian victory over the Ottomans in the 1770s, which gave breathing space to the Christian subjects of the Ottoman Empire. The conspiracy that led to the Greek Revolution started in the Russian empire. Later, Russia was one of the three Powers (along with Britain and France) to force the Ottomans to grant independence to Greece at the end of the War of Independence. The Greek George Washington (with a tragically different end than GW) was Ioannis Kapodistrias, a former minister of the Czar. For half a century following independence, there were three political parties: the English party, the French party and the Russian party (liberal-monarchist, liberal-republican, conservative). In all party systems following that, a pro-russian faction has always existed. During the 1960-1980s this also coincided with the progressive sections of the political spectrum (the pro-US faction was a far right military dictatorship that killed and tortured people). Throughout this, the religious connection has always been extremely strong, despite the recent scuffles between the Patriarchs.
In other words, there is a very, very deep connection between Russia in Greece.