Here is a really good quote on this topic. "Despite the significant adaptations, depending upon the audience, each gospel presentation has several core components. John Stott breaks them down into four basics, and calls them the gospel “events, witnesses, promises, conditions” (See J. Stott, The Message of Acts, p.79-81). Over and over again, the apostles talk about “gospel events” (Jesus’ death and resurrection for our sins), “gospel promises” (objective pardon for sins and subjective freedom and joy), “gospel witnesses” (the testimony of the Bible and the eyewitnesses to the resurrection), and “gospel conditions” (the requirements of repentance and faith)." (Evangelism: Studies in the Book of Acts, Timothy Keller, pg 46-47)