Jonas has always assumed that "Release" means expulsion from the Community and the Released person will live "Elsewhere." He believes this because everyone believes it; his own father is in charge of Releasing infants who are different, weak, or twins. Jonas is horrified that his father is actually killing the infants instead of sending them to a different Community; he realizes that his trust in his parents is based on their mutual indoctrination, instead of on the feelings that he now possesses.
"It's the way they live. It's the life that was created for them. It's the same life that you would have, if you had not been chosen as my successor."
"But he lied to me!" Jonas wept.
"It's what he was told to do, and he knows nothing else."
(Lowry, The Giver, Google Books)
Jonas has trouble coming to terms with the truth; he has always believed that his father's role in the Community was one of care and nurture, but he now sees that his father is just a pragmatic part of the collectivist society; his father does not possess the ability to understand the immorality of his actions, because he has been denied knowledge. Because of this, Jonas realizes that his father is simply one of all the adult drones operating under their strict orders; they have no conscious or independent thought of their own, and act entirely according to the wishes of the Community.