"And the crowds began to question him (John), saying, "Then what shall we do?" Some tax collectors also came to be baptized, and they said to him, "Teacher, what shall we do?" Some soldiers were questioning him, saying, "And what about us, what shall we do?"
"with many other exhortations...preached the gospel to the people." (Luke 3:18).
Most American Christians have likely never even tried to articulate the precise meaning of "the gospel". I think that they should. But be ready, because it might just rock your world, just as it did in the first century.