Charles Finney's sermon 'True Saints' emphasizes the distinction between three classes of professing Christians, focusing on the true friends of God who are characterized by their sincere benevolence, abhorrence of sin, and a deep desire to reconcile others to God. He highlights that true saints are not motivated by self-interest or public opinion but are driven by a genuine love for God and a commitment to holiness. Finney urges listeners to examine their own lives and motivations, stressing that true piety is marked by a relentless pursuit of the salvation of souls and a heartfelt prayer life focused on others. He challenges the congregation to reflect on whether they embody the characteristics of true friends of God and man, as defined by their actions and desires.