What is this verse actually saying?
1 Peter 4:6
ESV - 6 For this is why the gospel was preached even to those who are dead, that though judged in the flesh the way people are, they might live in the spirit the way God does.
For follow-up discussion and general commentary on the topic. Comments are sorted chronologically.
When Jesus Died he descended to hell where He preached to the dead (1 Pet. 4:6). Those who had died believing in the promise but not yet having received it were saved, those not believing the promise did not believe (Luke 16:30-31),
I think the best explanation and the most logical is "those who heard and believed the gospel but have since died".