David Wilkerson addresses the church of Ephesus, emphasizing that they have 'lost their first love' for Christ, which signifies a shift in their hearts where other priorities have taken His place. He highlights that despite their strong foundation in the gospel and exceptional teaching from Paul, their affection for Jesus has diminished, which is the first sin that grieves Him. Wilkerson warns that this message is relevant for all Christians today, urging them to examine their hearts and rekindle their love for Christ, as mere diligence and moral living are insufficient without a growing affection for Him.