What does Luke 12:5 mean?
A Pharisee invited Jesus to dinner with other Pharisees and their lawyers. After the host showed astonishment that Jesus did not ceremonially wash His hands before the meal, Jesus took the opportunity to explain plainly how the Pharisees' devotion to their extra-biblical laws was abusive to the people and led only to death. When a lawyer warned Jesus to back off, Jesus described how the lawyers were just the same as the Old Testament Jewish leaders who murdered God's prophets. In response, the men conspired to lead Jesus into saying something blasphemous enough they could justify His execution (Luke 11:37–54).Now, Jesus is building up His disciples to have courage under similar circumstances, not be afraid to speak the truth and publicly show their allegiance to Him when questioned before civil and religious leaders who seek a similar excuse to execute them (Luke 12:8–12). Because what is death? For Jesus' followers, it means their bodies will lie in the ground, and their spirits will go to paradise. After a time, they will receive glorified bodies and reign with Christ (1 Corinthians 15; 1 Thessalonians 4:13–18; Luke 22:30; Revelation 20:4–6). Paul so internalized this truth that he was torn between ministering or accepting death to be with Jesus (Philippians 1:21–23). Paul eagerly anticipated living true life in eternity and yet saw his earthly life as a "living sacrifice" (Romans 12:1) necessary to the kingdom purposes of God, thus he lived it joyfully (Philippians 1:24–26; 2:17–18).
The religious leaders have the authority to kill bodies. Far more terrifying is God's authority to consign unbelievers to eternal death in hell, outside of His loving presence (John 3:16–18, 36; Revelation 20:11–15). To drive the point home, Jesus uses multiple ways, here, to tell the disciples to fear God (Luke 12:6–10).
The disciples learn to embody Jesus' encouragement after they receive the indwelling of the Holy Spirit (Acts 2:1–2). They speak boldly before the Sanhedrin and, when they are beaten for their devotion to Jesus, they "[rejoice] that they were counted worthy to suffer dishonor for the name" (Acts 5:41).
This verse, itself, does not teach that hell is eternal, although other verses do (Matthew 3:12; 25:41; Mark 9:43–49). What it clearly shows is that God will judge people and send some to hell. The belief that everyone will be saved is not true.
"Hell" is translated from the Greek geenna, or "Gehenna:" the place of torment inhabited by the dead who did not worship God. The name is taken from the valley of Hinnom, southwest of Jerusalem. This was a trash heap where the bodies of criminals were burned. At one point, it was the site where Israelites sacrificed their children to Baal (2 Kings 23:10).