John Wyndham takes two directions in showing how values and beliefs affect behavior. He shows this through people who act positively because of their values and beliefs and through those who act negatively. Some characters who act positively because of their values and beliefs are David, Rosalind, Uncle Axel. Some who act negatively are Allan, Anne, David's mother, David's father, Spider man. There is actually a third special category not so easily divided into positive and negative: Sophie, the Sealanders, Angus Morton.
David, Rosalind and Uncle Axel are all led by their values and beliefs to watch out for others, protect others, have compassion and tenderness for others, love, accept and guard others--and themselves.
David's mother, Allan, the Spider man, Anne and David's dad are all led to judge, punish, reject, exile, expose, destroy, despise, dismember and disown other people. They will even turn on and disown their own family as with David's Aunt Harriet and David himself.
Sophie, the Sealanders and Angus Morton require some thought to understand. Sophie helped David to survive and return to the camp where the other telepaths were held captive. However, she didn't do it for the loving, protecting reasons that David might have done if the roles had been reversed (in other words, David might have saved Sophie in a similar situation). Sophie saved him to protect her own interests: She didn't want the Spider man to to take a woman other than herself. So even though her values led her to do good, her values were not the same as David's group.
The Sealanders came to rescue the telepaths and save them from danger--arriving just in the nick of time (Wyndham timed it this way to make a thematic point, not just for the suspenseful dramatic affect). They came as a result of the same values that David's group has. However, the Sealanders aid in demolishing the Waknukians, ensuring their deaths. They explain to David and the others that an inferior form of a species--one that cannot reframe their logical systems to accommodate a changing world--will come to warfare with the higher form of that species and must be wiped out and die.
This seems problematically opposed to the values of tolerance, inclusion and protectiveness. So even though they act out of the same values that David's group has, one of the results is the death of an attacking, murdering group of people--the key to understanding the paradox is that the Waknukians were attacking and killing, even their own sons and daughters.
Wyndham's thematic point, the one that requires the Sealanders to come just in time and no sooner, is that humanity's tendency to see events in the rigid logic of past events in the face of catastrophic events leads to their detriment and doom. He believes that it is necessary to build a new framework of logic--a paradigm of logic--when the world undergoes radical changes (perhaps like the social and climatic changes in the world today).
Angus Morton presents another problem. He actually doesn't do heroic or self-endangering good in the way that David, Rosalind and Uncle Axel do but he doesn't do bad either. What he does do is ridicule the community and leaders around him. He tries to trap Strorm into displaying ridiculous behavior about the horse and he reminds him of a past ridiculous act with the cat. He is the Moliere of Waknuk, the community satirist laughing at their seriously hypocritical beliefs and values contradicting a code of religion.