Don Carson says that we must be self-theologising, doing our own theological work in our contexts. John Owen, he says, didn't republish Augustine (though I'm sure he read him), he did his own work for his own day, standing on the shoulders of giants but not just repeating their words.
Lewis hits it:
“Our business is to present that which is timeless (that which is the same yesterday, today, and tomorrow) in the particular language of our own age. . . . We must learn the language of our audience. And let me say at the outset that it is no use at all laying down a priori what the “plain man” does or does not understand. You have to find out by experience. . . 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 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. A passage from some theological work for translation into the vernacular ought to be a compulsory paper in every Ordination examination.” via The Gospel CoalitionWe have to settle for saying less on every occasion, but in so doing we'll understand what we say and actually communicate something. I know the temptation to try and say everything in a half hour sermon, but trying to be exhaustive is exhausting, and I know as a listener that its better to say less and say it better. Sounds like hard work, but work worth doing. And, anything less is probably just shooting the breeze.