What is the spiritual reassessment that Jonas goes through at the end of the book The Giver by Lois Lowry?

Jonas's spiritual reassessment at the end of the book The Giver by Lois Lowry is brought about by the realization that his adopted brother, Gabriel, is about to be "released" (that is, killed).

Jonas begins to discover the truth about the ways in which his community's lifestyle is maintained after he gets the assignment to become the Receiver of Memory. When he reads the list of rules he is given, he is shocked to learn...

Jonas's spiritual reassessment at the end of the book The Giver by Lois Lowry is brought about by the realization that his adopted brother, Gabriel, is about to be "released" (that is, killed).

Jonas begins to discover the truth about the ways in which his community's lifestyle is maintained after he gets the assignment to become the Receiver of Memory. When he reads the list of rules he is given, he is shocked to learn that he is allowed to lie. This gets him thinking: who else in the community is allowed to lie, and what are they lying about?  That is his first step to understanding that a lot of things that he is used to in his life are actually not what they seem.

As Jonas "receives" the memories from the Giver, he learns about the strong feelings the citizens of his community are not supposed to experience: joy, pain, despair, love. He starts to doubt the wisdom of suppressing all feelings, positive and negative, in order to avoid the negative ones. He begins to wonder if feelings such as love are worth suffering for. He and the Giver decide to work out a plan to bring the memories back to the community.

Eventually the Giver allows Jonas to find out what the word "release" really means. Jonas is appalled because he has already received the memory of "death" from the Giver and knows what it is. When he learns that Gabriel is about to be released, he has to weigh the value of saving his brother's life, based merely on his love for him, versus the value of maintaining order in the community and preserving his personal safety. This is the spiritual reassessment he goes through at the end of the book.