I’m not saying they don’t believe in Christianity. But I suspect they’re treating this abundance of miracles instrumentally, as a way of psyching themselves up for the afterlife. If you asked them whether they thought scientific investigations would prove all these alleged miracles are legitimate, I doubt they’d be so naive.
What matters to these lay Christians, who are likely of an older generation, is the strength of their faith, not any intellectual justification of their religious beliefs. The more intellectual they are, the less likely they’ll see miracles around every corner, because they’ll be more aware of what science would have to say.
The Eastern Orthodox Christians want to come closer and closer to an experience of the divine, and that’s largely a subjective matter, since you can get there with altered stated of consciousness, produced by psychoactive drugs. Likewise, you can get there by drumming up fake miracles based on hearsay and baloney. So they turn up every week because of the religious experience they receive. The real cause of that experience is of secondary importance to them, at best.