In theological debates, Christians often point to 2 Peter 3:8 whenever they want to speak to God’s interaction with time:

2Pe 3:8 But, beloved, do not forget this one thing, that with the Lord one day is as a thousand years, and a thousand years as one day.

This verse is used to say that God is outside of time, or God experiences time in some sort of different manner (for than just regarding time differently). But in context, that explanation makes no sense. If placed in context, those understandings of the verse are not intelligible. The context is about a delay in the coming apocalypse:

2Pe 3:1 Beloved, I now write to you this second epistle (in both of which I stir up your pure minds by way of reminder),
2Pe 3:2 that you may be mindful of the words which were spoken before by the holy prophets, and of the commandment of us, the apostles of the Lord and Savior,

Jesus’ primary gospel was the coming of the Kingdom of God, an event in which angels would round up the wicked and kill them. Jesus preached that individuals should turn from their sins and hold fast. Peter here is reminding his listeners of both these things. By the time 2 Peter was written, doubts about the coming apocalypse were circulating. Peter sets up the reader to address this particular point. He continues:

2Pe 3:3 knowing this first: that scoffers will come in the last days, walking according to their own lusts,
2Pe 3:4 and saying, “Where is the promise of His coming? For since the fathers fell asleep, all things continue as they were from the beginning of creation.”

Christians or former Christians were beginning to spread doubts about the second coming. “Where is the promise of his coming?” We see an element of time has passed: the “fathers had fallen asleep”. The problem was that people began “walking according to their own lusts”. Peter was confronting a general rebellion against the ministry of Jesus, a brooding skepticism. Peter next reminds them that judgment was historically real:

2Pe 3:5 For this they willfully forget: that by the word of God the heavens were of old, and the earth standing out of water and in the water,
2Pe 3:6 by which the world that then existed perished, being flooded with water.
2Pe 3:7 But the heavens and the earth which are now preserved by the same word, are reserved for fire until the day of judgment and perdition of ungodly men.

God created the earth and previously destroyed it. Peter’s critics were Jews and believed as much; they just now rejected Jesus’ message about coming doom. Peter appeals to their belief in Noah’s flood. And then Peter claims they are wrong to think a similar judgment is not imminent. It is in this context, Peter utters those famous words:

2Pe 3:8 But, beloved, do not forget this one thing, that with the Lord one day is as a thousand years, and a thousand years as one day.

Peter is not shuffling in some unrelated statement of God being outside of time. This would not make sense in context: “Be assured the end is nigh, because God is outside of time.” That is not what this verse is communicating. Instead Peter is offering reasons why the apocalypse has been delayed and offering assurances that it will soon come to pass.

One day is as a thousand years. God is powerful and could bring to pass His grand plan in one day, in the time it would take people thousands of years. Even if people do not see signs that the end is nigh, one day is all it takes for God to accomplish His will.

A thousand years is as one day. God is patient waiting for repentance. God could wait a thousand years, and it would be as man waiting patiently for one day. That is the contrast.

Peter reinforces this idea:

2Pe 3:9 The Lord is not slack concerning His promise, as some count slackness, but is longsuffering toward us, not willing that any should perish but that all should come to repentance.
2Pe 3:10 But the day of the Lord will come as a thief in the night, in which the heavens will pass away with a great noise, and the elements will melt with fervent heat; both the earth and the works that are in it will be burned up.

So Peter’s argument is that people should be prepared because the apocalypse could come at any moment, any day without foreshadowing. It has only been delayed because God is allowing time for repentance. This reinforces the ideas of the previous verses. Verses 9 and 10 are an explanation of Peter’s metaphor in verse 8! Peter concludes:

2Pe 3:11 Therefore, since all these things will be dissolved, what manner of persons ought you to be in holy conduct and godliness,
2Pe 3:12 looking for and hastening the coming of the day of God, because of which the heavens will be dissolved, being on fire, and the elements will melt with fervent heat?
2Pe 3:13 Nevertheless we, according to His promise, look for new heavens and a new earth in which righteousness dwells.
2Pe 3:14 Therefore, beloved, looking forward to these things, be diligent to be found by Him in peace, without spot and blameless;

Peter reminds his audience that the apocalypse would happen and Peter tells them to remain righteous because the end was coming. Peter was giving credibility to the premise that the end could come at any time and an apology as to why it had not happened as of yet. Peter uses the time illustration for this end. Peter was not interjecting a strange metaphysical concept in the middle of a pointed passage.

What is really interesting is that Peter was trying to convince people that the apocalypse would happen in their own lifetimes, not thousands of years in the future. This entire passage is a plea to prepare for the end, not a claim that the apocalypse would not soon happen. When Augustinian Christians try to explain 2 Peter 3:8, they need to explain how it fits in context. What was Peter communicating in the overall passage? What are his points? How does the time metaphor fit the overall theme? Without this, the verse is unintelligible.