The three hermits in Tolstoy's short story may be deeply devout holy men, but, as the bishop discovers, they have a complete lack of understanding when it comes to basic Christian doctrine. For good measure, they don't even know the words to the Lord's Prayer, otherwise known as the “Our Father.”
The bishop seeks to remedy the hermits' ignorance by teaching them how to say the Lord's Prayer. At first, the men stumble over what to them are unfamiliar words, but the bishop persists and gets them to repeat the words of the prayer over and over again until they've finally committed them to memory.
After the bishop leaves the island where the hermits live, he is astonished to see the three men run across the surface of the water after his boat. Once they've caught up with him, they tell him that they've forgotten the words of the Lord's Prayer because they stopped saying them for a time. They want the bishop to teach them again.
But the bishop, who's now humbled by the simple, unsophisticated faith of the hermits, tells them that it's not for him to teach them. He sends them on their way by urging them to “pray for us sinners.”