What does John 8:44 mean?

Jesus' critics have adamantly resisted His teachings. In part, this has hinged on their claims to be the children of Abraham (John 8:33). Jesus responded by pointing out that "true sons" behave as their father did. Since Abraham believed God, and these men do not, they are not part of Abraham's spiritual family. Instead, they are the children of some other father. So far, their conduct has been marked by violence (John 5:18), deception (John 7:21–24), and hypocrisy (John 8:1–11). They reject the message of Christ because they do not want to hear it (John 8:43). They've even insulted Jesus' family by insinuating that He is an illegitimate child—a "son of fornication" (John 8:41). Here, Jesus completes His statement about the true spiritual father of these critics, in spectacular fashion.

In no uncertain terms, Jesus states that these hateful enemies are, in fact, the spiritual children of the devil. He refers to murder, resistance to the truth, and lies—all of which were part of His earlier criticism of these men. This is not a soft, timid response on the part of Jesus. This is an open, overt rebuke delivered against religious leaders who are leading others to hell (Matthew 23:15). Contrary to the caricature of Jesus as a fragile mystic, passages such as these prove His ability to present righteous strength.