Isaac is not a child

I have read the short story and know that in it Isaac is nine. However, Job's line suggests that Isaac is not a young person. A kid would refer to the early or middle childhood of another kid as the time when someone is 'little' or 'small', not 'young'. Isaac has a highly manipulative, authoritative air that a child, even an unstable one, would not bear. He carries a fervor for wholly controlling lives whereas the original version presents the preacher as one who simply wants to be agreed with and followed solely for religious reasons. Isaac holds sophistication that he lacks in his debut in which he seems closer to an evangelist than a cult leader. Also, the movie is very different from its predecessor. Perhaps the film gives Isaac's character an update to accommodate a grown actor. I realize that we cannot be sure of the age of Isaac, but strongly get the impression that he is an adult.