For to this end was the Gospel preached even to the dead, that they might be judged indeed as men in the flesh, but live as to God in the spirit.
Peter had in mind believers who had heard and accepted the gospel of Christ when they were still alive, but who had died by the time Peter wrote this letter. Some of them, perhaps, had been martyred for their faith. Though these were dead physically, they were triumphantly alive in their spirits (cf. Hebrews 12:23). All their judgment had been fully accomplished while they were alive in this world (“in the flesh”), so they will live forever in God’s presence. - MSB