I just realized that some years ago, in 2012, a surveywas made in Russia regarding religious affiliations. It gave the following numbers in percentages :
- orthodox from Moscow Patriarchate : 41%
- believers without religion : 25%
- atheist : 13%
- muslims : 4.7%
- and orthodox not belonging to the Moscow Patriarchate and not old believers : 1.5% in Russian "Православные вне Церкви"
I tried to see the situation in some regions (oblast) to check if they were not confused with another religion, in particular the Armenians that might answer they are orthodox. It appears that in general these people are in majority ethnically Russian generally in the same proportion as the global population of the region. Sometimes they have 3% of ethnic Armenians compared to 1% in the global population in the region, which indicates there was no massive confusion with the Armenian factor. So possibly, this 1,5% of the global population might represent the true orthodox in Russia. It would mean more than we could generally think.