The book of Acts recounts the spread of the early church and the manner in which Christ works to take the gospel from Jerusalem, to Samaria, and finally to the end of the earth (Acts 1:8). Your sermon from Acts 6:8–15 must provide an introduction to Stephen, helping God’s people to understand the circumstances around his arrest and trial as well as what we can learn from him. In terms of application, you want to help the believers understand that opposition and persecution is something we should expect, and we can prepare ourselves by meditating on God’s promises and striving to be faithful to him in our day-to-day living.