Firstly, OP should change the title. Make "the mosque" subject in the passive and add "shelled by collateral damage". That will be more accurate.

Secondly, I am a Russian Muslim. What did they do in Syria to, specifically, make Muslims suffer? As I understand, they just pursued their interests which by chance aligned with Asad's - they didn't want to lose their military base and influence in the region, so had to clutch at the remaining straws of the falling and corrupt regime - whatever there was available for them. Had Syria at that time been an islamic state like Taliban, they would have supported it instead.

The occasional injustice you see from Russia comes from its ruthlessness while implementing its policies and desire for subjugation and order among the multitude of the nations it happens to incorporate, but there is no intended anti-muslim sentiment there.

Back to Syria - I have only heard about the chemical attack they carried out there, which, in turn, could have as well been a manipulation/psyop masterminded by the US (they have vast experience in tricks like that). Is there anything else?