Right, good point, FMF, even the category itself can feel a little bit funny, but I understand it as a category as it can be a particular interest.
For instance, "Korean Christianity" and "Spanish Christianity" can be interesting in the sense of studying the development and history of Christianity in those societies.
Yet, the category can also be funny because a Korean Lutheran and a Korean Catholic have less in common with each other theologically than a Norwegian Lutheran has with a Korean Lutheran, and a Spanish Catholic with a Korean Catholic.
It is worth noting, though, that "Korean Christianity" is a very interesting topic as it involves a lot of very recent and relevant stories about the entrance of Christianity, particular sects of Christianity, and the role of the Christian minority in its modern history.
Moreover, the very unique characteristics of Korean culture can end up with unique questions...
For instance, the way that Orthodox, Catholic, and Protestant people may approach traditional ancestral rites practices on holidays.