I'm not Russian, but my family is. And while my family members are open and accepting, I do understand some of the cultural factors. I'm not excusing it, just showcasing why there is so much hate.

Russia is a very family based culture, like very family based, which I would attribute most of the homophobia to (moreso than religion). Women and men are focused on finding "a good partner", so they can have children and support the parents when they are in their early 20s. This means that gay people are seen as a threat to family values and the family structure, as they can't have biological children. This is the same in China, despite it being an irreligious country.

Secondly, gay people are expected to "keep quiet" or "keep it in their bedroom". This isn't as malicious as you would expect, PDA is SEVERELY frowned upon in traditional Russian culture. Like, holding hands in public and kissing is apparently seldom seen. Despite the fact I know my Grandparents were in love with each other, I very rarely saw them hold hands and have never, ever, saw them kiss each other. This contradicts with modern gay Russians, since they allign with the west (rightly so) and adopt the "out and proud" philosophy. This gets people REALLY angry, and while they would be angry at a straight couple, they see gays as a problem since it is disproportionate. So they see them as perverted.

Lastly, Russians are very religious and follow a very non-relaxed/conservative brand of Christianity called Russian Orthodoxy (same as most of East Europe and Greece). For context, most women cover their heads and until recently most churches were separated by sex (one half of the church, the other for women).

Add in the fact that Russia is a "masculine" culture, they find the idea of a man being submissive disgusting.

Unfortunately that's just the way Russian culture developed and it needs to be changed.