Rhetoric is deeper than what is said, more than well spoken words, more than clear or persuasive speech. Rhetoric most often involves language, but it also includes lifestyle and liturgy.
Paul’s life was a tool of persuasion. He commanded the Corinthians to use their personal rights for sake of others rather than themselves (1 Corinthians 8), and he modeled this very behavior (1 Corinthians 9). Not only was what he said not undone by what he did, what he said was more effective because of what he did.
The liturgy of the Lord’s Table also speaks, but without words. Paul told the Corinthians that “as often as you eat this bread and drink the cup, you proclaim the Lord’s death until he comes” (1 Corinthians 11:26). But how?
Just as Paul provided an example of the gospel of the cross by giving up his personal rights for the sake of others, so we announce the gospel of the cross by giving up our personal grievances against others. We stop judging others wrongly, and judge “ourselves truly” (verse 31). We eat and drink in fellowship because our envy and bitterness and anger is dead at the cross.
The gospel is news. It can (and must at some point) be spoken and heard, written and read. The message cannot be altered because it is historical reality. But our lives can adorn the doctrine, and they should show the truth of the gospel, that sacrifice driven by love for others changes the world.