"Preach the gospel; use words if necessary" goes hand in hand with a postmodern assumption that words are finally empty of meaning. It belittles the high value that the prophets, Jesus and Paul put on preaching.
Of course we want our actions to match our words as much as possible. Our actions should support what we preach. But the Gospel is a message, a proclamation, news about an event and a person upon which the history of the planet turns. Unless the Gospel is actually proclaimed with our lips, no one will know what it means.
We must tell them that God made them along with the rest of creation. That despite being loved by God and made in his image we rebel against him in sin, trying to run our own lives, instead of loving God. The result we deserve is hell. Yet the Holy God who judges sin also loves rebels and is willing to forgive, and so sent Jesus to die in our place for our sin; past, present and future. More than that, Jesus came back to life, never to die again, to reign as the King over all things. Therefore, it is him we must trust; it is him we must love; it is him we must serve. That is what we must preach in order to see the lost get saved, and to see the saved become committed disciples of Christ. We must never change that message, nor must we shrink away in fear from telling anyone this incredibly good news of Jesus Christ.
"How are they to call on him in whom they have not believed? And how are they to believe in him of whom they have never heard? And how are they to hear without someone preaching?" (Rom. 10:14).