I ran across this little gem in God in the Dock. It is in a letter Lewis wrote to The Christian Century.
"In both countries an essential part of the ordination exam ought to be a passage from some recognized theological work set for translation into vulgar English - just like doing Latin prose. Failure on this paper should mean failure on the whole exam. It is absolutely disgraceful that we expect missionaries to the Bantus to learn Bantu but never ask whether our missionaries to the Americans or English can speak American or English. Any fool can write learned language. The vernacular is the real test. If you can't turn your faith into it, then either you don't understand it or you don't believe it."
Church members complain about this all of the time. "My pastor talks in a way I don't understand." I need to hear this as well as any other pastor.