What does John 8:56 mean?

Once again, Abraham is invoked in this debate. The critics attacking Jesus placed enormous importance on their descent from Abraham (John 8:33). Jesus has pointed out that spiritual matters, not genealogy, make a person a "true son" of Abraham. By that measure, those who lie and kill are acting like their true spiritual father, the Devil (John 8:44). Continuing this idea, Jesus has directly called His critics liars. They do not know God (John 8:47), and do not want to know God (John 8:43), which is why they reject the One sent by God.

Jesus has said that those who accept His words will "never see death" (John 8:51). His critics misunderstand this as a reference to physical death. Jesus, however, is referring to salvation. Here, He clarifies by saying that Abraham's faith looked forward to the Promised One—and Jesus is that One. Therefore, when Jesus claims to bring a message which frees men from death, that message includes those who came before Him, such as Abraham.

In making this statement, Jesus implies that He witnessed Abraham's life in a direct, personal way. This, as shown in the next verse, results in another dismissal by His critics.