It’s one of the best children’s books of the 20th century, and IMO the best SF children’s book ever written.
Some reasons why the book is frequently challenged:
- Euthanasia/Capital Punishment: It isn’t just a child being euthanised. The term the book uses is ‘released’, which the readers come to realize means “killed”, and this is the ultimate fate of every person in the community. The elderly are released when they reach the point that they are determined to no longer be useful. Criminals are released for major crimes or for a series of minor crimes. Children who don’t meet standards are released.
It’s implied that the community, or possibly a group of communities (it isn’t clear) is at war, and when one of the pilots accidently overflies the community, he’s released.
Torture: Jonas is actively tortured by the Giver. The Giver stores memories of intense emotion, both good and bad, for the community. He passes on these memories to Jonas. As the Giver must be the repository of all of these memories, Jonas must experience over a period of years every possible painful experience a person can so that the Community can be protected from them.
Family structure: Couples are assigned to each other, and their children are created through artificial reproduction and assigned to a family at the correct age, resulting in families in which nobody is related. Husband and wife don’t have sex.
Sex: Sex is banned. As soon as a child starts having sexual desires, he or she reports it to a parent and is started on drugs to eliminate the desire entirely.
Conformity/Uniformity: Everyone is expected to behave in essentially the same way. People aren’t valued as individuals (thought they are told and believe they are) but for how well they perform their function in society. Thus, though there are different jobs in the community out of necessity, everyone is expected to exist within a very narrow band of conformity.
People in the community almost universally see all of these things as good for the people and the community (with the exception of being ‘released’ which most believe means 'sent someplace else). This community acceptance of the status quo is sometimes misinterpreted as the book promoting these ideals.
- Finally, Jonas rebels, taking a baby about to be released and running away. He escapes the community, but in the process is caught unprepared outside the weather controlled community (weather controlled as in there isn’t any–perfect weather all the time) and both he and the baby die in a snowstorm.*
The book has a very dark tone, which offends some self-appointed censors, and the totalitarian society offends others. Others are offended that it isn’t just a case of the community being evil–it has many positive aspects to it–so that it isn’t a simple case of good vs. evil, but about a person forced to make a moral choice–which has been interpreted as “teaching values”.
*As he and the baby are close to freezing to death, Jonas begins to see the same things he saw in happy memories given to him early in the story–the pleasent memories that he kept returning to again and again in painful times earlier in the book, and which he kept asking the Giver for more of. This is either the most inappropriate pasted on happy ending of all time, or he dies hallucinating with no one coming to his rescue. Many take the ending at face value, but I think they’re missing the point.[/spoiler]