This Sunday School lesson examines the jurisdiction and theological implications of 1 Corinthians 1:2, emphasizing that the epistle applies universally to all believers who claim Jesus as Lord. It distinguishes between positional sanctification at salvation and the practical call for Christians to live holy lives distinct from the world. The lesson argues against unrealistic standards for church membership, asserting that God has a greater tolerance for assemblies than we might think, while maintaining their status as churches. The lesson addresses related subjects like the definition of a saint, the necessity of church discipline, and the responsibility of believers to obey their calling to holiness in daily conduct.