Well, going by figures for attendance in Easter Services, more Ukrainians (10.9 million) in Ukraine attended Church than did Russians in Russia (8 million)on Easter; quite astonishing given Russia's and Ukraine's relative populations.
Add to this that the areas in Ukraine with the highest Church attendance were those of the Ukainian Catholic heartland (Lviv: (1.6 million); Zakarpattia (790,000), Ternopil (700,000), and one could reasonably assume Ivano-Frankivsk oblast's attendance equivalent to Ternopil's, than one could assume that the heartland of Ukrainian Catholicism's numerical output is equal to Half! of the entire Easter church-going population in Russia.
http://risu.org.ua/en/index/all_news/culture/religious_holidays/35131/Ukrainian Catholics may be a minority, but the oblasts in which they are concentrated are among the most religious. A very vocal minority and a sizable proportion of all active Ukrainian religious. No wonder Moscow tried so hard not to lose Halych. And if it were to lose Ukraine too, so much for the Moscow as Third Rome.
The question is also why does the Patriarch of Moscow feel it important to change a name of a street such as Mazepa in Ukraine's captital Kyiv. He is now in effect telling Ukrainians in their independent nation what to call their roads. He might moan at Mazepa, but says nothing at all of the communist streets Leninskaya, Dzherdzhinskaya, KarlMarx, etc. No objections to streets named after these communist killers. No he focuses on Mazepa.
http://www.risu.org.ua/en/index/all_news/state/national_religious_question/36039