It’s a very strange text, indeed, because the language Peter uses is not even the standard NT words used for death (hades) or gehenna (‘hell’).

First, a word about the author. While Peter is classically treated as ‘unlearned,’ these epistles demonstrate genius in the rhetorical arts. My opinion is that Peter’s protege, Mark, may have written it, as he also wrote Peter’s version of the Gospel.

Inside the rhetorical style and agenda of these epistles, we find ‘Peter’ borrowing the Greek mythological term tartarus (translated here ‘hell’). Tartarus was the mythological prison into which the Olympian gods cast and bound their enemies, the Titans, originally the twelve children of Uranus (heaven) and Gaia (earth).

Your question then multiplies dramatically. Did the Greeks believe these stories literally? Not so much. Well before the first century, they sought to understand and interpret mythological poetry for what they represented. So then, what did their mythology represent in their minds? And why did Peter decide to borrow that in his context? And why would he reframes and transpose the apocalyptic stories of the Jewish bestseller, Enoch, into a Greco-Roman context? What is he up to, rhetorically? These questions are not hopeless mysteries. We’d just have to start by ask what the angels of Enoch or Titans of Greece would represent in his case?

In Peter’s letters, he is addressing a particular political situtation involving intense persecution by the imperial powers who will soon kill him (or had just martyred him, if Mark is writing in his memory). The theme of the letters is how to endure the suffering at the hands of the ruling ‘powers’ that they cannot avoid. How can we think of the gospel as victory and how can we understand martyrdom as overcoming?

Into that discussion, Peter raises the topic of Jesus’s cruciform victory over death, darkness, and dread. It seems very likely that this is the connection he’s making … at the Cross, the powers and the ways we represent them have not defeated Christ. In his suffering, they are conquered, driven out, and confined. Yes, their persecutors still employ the sword and the cross against the Lamb’s flock, but death and the fear of death are bound up.

The moral of the story is, then, to patiently endure the persecution without compromise to fear (by renouncing your faith) or hatred (by joining the insurgency). Live in love, in truth, in service to Christ and one another. Whatever the Titans represent spiritually (the forces behind Rome’s tyranny), Christ is Lord and they are not. Therefore, hang in there, even if it means passing through the defeated gates of death into eternal life.

So the context into which the letter is being shared and what Peter wants to accomplish in his readers tells us why he’s using these mythopoetic images. But to literalize them as if he were trying to teach pagan cosmology to Christians would be a great (mis) adventure in missing the point by plucking a few verses out of context.