Peter says something in chp 4 about the gospel that has perplexed many for centuries:

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 men in regard to the
body, but live according to God in regard to the spirit.

The NIV adds the word “now” before dead to clarify. The NRSV has just “the dead.” Which is the problem: Who are they? Three options: (1) those who were preached to after Jesus’ death who were in prison (1 Pet 3:18), (2) the spiritually dead who are now alive in Christ, and (3) those who were alive, heard the gospel, but are now dead. This third option seems the most persuasive to most commentators.

The big point here involves these observations:

First, that gospel preaching must be preached to all as the great Wesley did.

Second, that humans are accountable to God and gospel preaching “in the body” (during our earthly life) correlates with what happens in the new heavens and new earth (in the spirit).

Third, that gospel preaching judges sin.

Fourth, that a positive response to gospel preaching leads to life before God.