1 Peter 4:6 For this is the reason the gospel was preached even to those who are now dead, so that they might be judged according to human standards in regard to the body, but live according to God in regard to the spirit.
This verse adds to the mystery of this letter along with 1 Peter 3:19-20. In the context, this verse completes the idea of verse 5 and the idea that everyone will give an account to God. A question of the verse is about whom it refers. Who did the preaching, and who are the dead? Related to this is when and where the preaching took place. The dead could refer to those who had died to whom Jesus preached in 3:19. It could be timeless and refer to the spiritually dead who have the gospel preached to them. It would also refer to the new believers in Asia-Minor who had died before Peter wrote this letter. As 1 Thessalonians implies, some early Christians struggled with death as they awaited Jesus’ second coming. The third option makes the best sense in light of biblical theology. Those who had died would be judged fairly by God, who would know of their struggles for their new faith. Some could have lost their life because of their faith in Jesus. God new the commitment of those martyred for their faith and would reward them accordingly.
God is just and will judge both the living and dead. How can God judge the dead if they have not had opportunity to put their faith in Jesus? Another issue is to determine what “dead” means. Is this dead physically or dead spiritually? The intended outcome of the preaching of the gospel is to bring life to those who are dead. Peter seems to indicate that these people are dead physically and not part of this world but alive spiritually in eternity. The grammar of this passage indicates that the reason the gospel was preached to the dead was so that they might be alive in their spiritual state.
Peter’s overall purpose in this verse and the surrounding context seems to be to encourage his readers to endure suffering, realizing that there is a reward for victory in the struggles of this life. Those who cause Christians harm will give an account for their actions and will be judged by God, who is just. God is just and will not judge the dead according to a message they have not heard. If God is so just, we should be motivated to live accordingly.