The Chrysalids - At the end of chapter 3, David's nightmare shows us how he's starting to understand the dark side of his father's belief in the evil of Blasphemy.
Explain how David's nightmare does this. [pages 27 and 28]
David's nightmare reveals his increasing apprehensions about his father's capability of eliminating whatever he deems is not "PURE," whether it be animal or human. Early on, he has become aware of his father's religious fanaticism as their community has more Purifications than others. His father seems extreme in his eliminations of those he deems impure.
After scolding his son before all the others assembled for dinner, his father later visits David in his room before the boy goes to sleep in order to berate him further for his "blasphemy" of finding fault with the "Norm." (Earlier David has made what he has assumed to be a harmless comment about needing an extra hand to assist himself with a bandage.)
In addition to his father's reproaching of his son David for what the boy has thought was an innocuous remark, David recalls having heard members of the community remarking upon Mr. Strorm's stringent insistence upon Purity. With these experiences on his mind, David has a disturbing dream in which
We were all gathered in the yard, just as we had been at the last Purification....this time it was a little girl, Sophie, standing barefooted and trying uselessly to hide the whole long row of toes that everyone could see on each foot.
David worries that if his father can humiliate him so quickly and strongly, and he can eliminate any creature deemed impure with brutal alacrity, he may be able to execute a human mutant just as swiftly.