You must translate every bit of your Theology into the vernacular. This is very troublesome, and it means you can say very little in half an hour, but it is essential. It is also of the greatest service to your own thought. I have come to the conviction that if you cannot translate your thoughts into uneducated language, then your thoughts were confused. Power to translate is the test of having really understood one’s own meaning.
C.S Lewis in Christian Apologetics quoted in C. S. Lewis – A Life: Eccentric Genius, Reluctant Prophet