The second of two letters from Peter to God’s chosen people in Pontus, Galatia, Cappadocia, Asia, and Bithynia (in modern-day Turkey): 2 Peter 1–3
God does things in His own time. He keeps a promise as if He made it yesterday, even if He made it a thousand (or more) years ago:
2 Peter 3:8-9 But you must not forget this one thing, dear friends: A day is like a thousand years to the Lord, and a thousand years is like a day. The Lord isn’t really being slow about his promise, as some people think. No, he is being patient for your sake. He does not want anyone to be destroyed, but wants everyone to repent.
But some people have made much of the idea that there is a set scale that somehow equates one thousand years to a day. Psalms has something to offer here:
Psalm 90:3-6 You turn people back to dust, saying,
“Return to dust, you mortals!”
4 For you, a thousand years are as a passing day,
as brief as a watch in the night.
You sweep people away like dreams that disappear.
They are like grass that springs up in the morning.
In the morning it blooms and flourishes,
but by evening it is dry and withered.
This part of the Psalm emphasises how short our lives are compared with God’s eternal view. And on top of that, the second half of verse 4 has a thousand years likened to a night watch, which would usually be three hours. Suddenly, that single day is now expanded out to not one thousand years but eight thousand years (1000 years multiplied by 24/3).
The verse from 2 Peter suggests it can also go the other way. God can look at a thousand years and see it as nothing more than a day or a few hours. If you want to use a set scale (of 1000 years to a day), then it means He can also look at our day and see not a thousand years, but one-thousandth of a day (or just under two minutes), or even one-eighth of that (about 18 seconds).
So it’s probably not worth getting hung up on the maths.
The main thing from all this is that God keeps his own time. If He makes a promise, for example about Jesus coming back, it will happen, but maybe not in the timeframe that people expect:
2 Peter 3:3-4 Most importantly, I want to remind you that in the last days scoffers will come, mocking the truth and following their own desires. They will say, ‘What happened to the promise that Jesus is coming again? From before the times of our ancestors, everything has remained the same since the world was first created.’