What does Acts 23:6 mean?
The Roman tribune wants to know why a mob of Jews attacked Paul in the temple (Acts 21:27–34). He brings Paul before the Sanhedrin hoping the Jewish religious leaders have some insight. Paul tries to tell the Sanhedrin about Jesus. Before he can begin, he finds himself in an argument with the corrupt high priest (Acts 23:1–5). Paul realizes he's not going to get a fair trial, let alone an opportunity to reach these people for Christ, so he changes tactics and instigates a fight between the Pharisees and Sadducees.Even so, Paul's strategy gives the Pharisees something legitimate to think about. Pharisees can become Christians while remaining Pharisees: men staunchly committed to following the Law of Moses. However, in practice, they often struggle to fully accept grace and abandon their inflated sense of self-worth (Galatians 6:12–13). Sadducees, on the other hand, must give up a main tenet of their faith; they believe there is no bodily resurrection from the dead.
This "hope" has a couple of different facets. Paul will tell King Agrippa that the hope is the fulfillment of God's promises to the Israelites given in the Old Testament (Acts 26:6–8); this includes the salvation of the Gentiles (Genesis 12:3). Paul tells the church in Corinth resurrection from the dead is necessary for the prophecies to be fulfilled (1 Corinthians 15:3–5). Jesus' resurrection and glorification shows us what His followers can expect after death.
The ultimate hope of the Jews is in God's promise of a Messiah who will lead them to a peaceful, affluent land. This will happen in the millennial kingdom. Those faithful Jews who die before then will still experience God's blessing in their resurrected bodies.
All of this most likely goes over the heads of the Sadducees. They're more interested in defending the honor of their high priest and re-engaging in the continued war about the resurrection with the Pharisees. Before long, the two sides are fighting and the tribune grabs Paul and retreats to the barracks (Acts 23:10).