To the Jews who had believed him, Jesus said, “If you hold to my teaching, you are really my disciples. Then you will know the truth, and the truth will set you free.” John 8:31-32
The setting here is Jesus talking to elite Pharisitical Jews. The Pharisees were knowledgeable and well schooled in the word of God. They were gatekeepers, testing those who made claims on God. Only the tests did not allow success. When faced with Jesus, they did not know him. And Jesus does not abandon them, but draws a clear line.
Jesus points out who the parents are of those who would kill him. The children of Abraham welcome God. And so those who would kill him were not the children of Abraham. This is very upsetting for those who wanted him dead who felt Jesus had failed their tests. Today, the quote about knowing the truth and the truth setting the truthful one free is the cornerstone of the CIA’s original headquarters.