When I teach that the persons of the Trinity live in eternal perichoretic unity, I am not merely making an ontological, first-order claim about the nature of reality — though I am doing that. I am not teaching “timeless truth” that has to be “applied” to the ever shifting realities of an historical community. Rather, I teach the Trinity as a way of regulating the language and practice of the Church, especially her language and practice in worship. Properly, all teaching is application.
-Peter Leithart, Against Christianity, 44.