Every question is settled by asking, "What did previous generations believe?" And since previous generations asked the same thing, the snowball just keeps getting larger. Against that weight of accumulated witness, a notion that blew in on the cultural breeze doesn't stand a chance.
What's surprising is that there is so little variation from culture to culture. As missionaries carried Christianity to new lands, each new outpost looked back to the "faith once delivered." So Russian, Greek, Romanian, Antiochian and other Orthodox all share the same beliefs. Even the Oriental Orthodox, the Armenians and Copts and others, who have been separated from us since the fifth century, still look an awful lot like us. They, too, are looking back toward the authoritative early faith.
So someone who wanted to challenge Orthodoxy would not be able to locate a building to hold a protest march in front of. The faith is too diffused. And what if a high-ranking hierarch attempted to enforce innovations? He'd be recognized as a kook and rejected. Anyone who disagrees with the inherited faith has stepped outside the building.
Although we don't have innovation, we do have nominalism. Lots of Orthodox go to church every Sunday but don't know much about the faith. Yet they know that there is something that they don't know much about. They don't try to redefine "Orthodoxy" to cover whatever they're doing or not doing. If they're dissatisfied, if they want something more contemporary, if they want to attend a more "American" church, there are plenty they can choose from.
And meanwhile, of course, lots of people are coming in the other door. The Dallas Morning News reports that, in the Antiochian Archdiocese, 78% of the clergy are converts. This means an infusion of parish leaders who are very well-informed about theological and cultural issues, and very intentional about why they have become Orthodox (sometimes at great personal sacrifice).
So instead of spending the last fifteen years fighting and worrying and being bruised in a hostile denomination, I've been able to focus on the face of Jesus Christ. I've been able to dig deeper into awareness of my own sinfulness, and take baby steps toward spiritual healing. I'm able to worship in an ancient communion full of awesome beauty, one that is now being blessed with quiet revival. My one regret? That I didn't do it sooner.