How should believers correct someone who is missing important truth?

Les explains that Apollos was already mighty in the Scriptures, publicly showing from the Old Testament that Jesus was the Christ, but he could go further into Paul's gospel: Christ died for the sins of the world, was buried, and rose from the dead. It took two common, ordinary people to bring him that further revelation. Les tells his people and television audience not to do it with pride or sarcasm, but humbly and by the grace of God to approach such people—even a Sunday school teacher—and say, 'wait a minute, you're missing so much,' and point it out. Be skilled in the use of this book, able to say what the book says and that they are missing it. If they are like Apollos, they will take it to heart, and you gain a more informed teacher or pastor, and appreciate his love and concern for you and his congregation.