“Are mono-ethnic churches biblical?”
I have never been to a truly mono-ethnic church. I have no evidence they exist. To remain truly mono-ethnic for more than a few weeks, a church would have to find a way to enforce ethnicity-based membership. Which leads to the obvious question: What makes a person, for example, Chinese? Is 100% racial “purity” required? Or would it be permissible for him to have one Tibetan grandparent, or if not a grandparent, perhaps a great-grandparent?
How would you prove such a thing, and why should you have to?