The main theme of The Giver is that differences should be celebrated instead of feared. Choice is instrumental to our humanity.
An example is when Jonas is given the memory of grandparents, and experiences love for the first time.
"I will. I am left with a vague wisp of that one; and I have many other memories of families, and holidays, and happiness. Of love." (p. 125)
Jonas comments that it is an impractical way to live, but he enjoys the experience of love. Love is absent from the community because people may not make the best choices, and might experience pain. However, the pain is worth it because where there is love, there is also joy.
A second example is when Jonas’s father releases the newborn twin. Before Jonas sees the release, he comments on why the identical twins are considered unnecessary in the community.
"Well, they can't have two identical people around! Think how confusing it would be!" Jonas chuckled. (p. 146)
The community has placed the threat of confusion as more important than the life of the twin. After Jonas sees what release really is, he is horrified. He realizes his mistake, and his community’s mistake.
The final example is that the community tries to avoid having people make their own choices, in case they have to make the wrong ones.
"Definitely not safe," Jonas said with certainty. "What if they were allowed to choose their own mate? And chose wrong?
"Or what if," he went on, almost laughing at the absurdity, "they chose their own jobs?"
"Frightening, isn't it?" The Giver said. Jonas chuckled. "Very frightening. I can't even imagine it. We really have to protect people from wrong choices." (p. 98)
This relates to the theme because the community has chosen to eliminate choice, and the result is that no one is significantly different than anyone else.