Are there religious people in churches today who are devout and sincere but still lost?
Yes. Scripture indicates that churches can be filled with people who resemble Cornelius: devout, sincere, prayerful, and generous, yet still unsaved. Peter was sent to tell Cornelius words by which he and his household would be saved, showing that religious devotion and good works do not themselves save.
Les explains that Cornelius was devout, prayed, gave alms, and believed in God, yet the angel told him to call for Peter, who would tell him words whereby he and all his house would be saved. Since that was still future, Cornelius was not yet saved. Les teaches that the lesson is the same today: churches are full of people like Cornelius—devout, sincere, praying, and giving—but lost. It is a sad story, but true.