But you must not forget, dear friends, that 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 to return, as some people think. No, he is being patient for your sake. He does not want anyone to perish, so he is giving more time for everyone to repent.
But the day of the Lord will come as unexpectedly as a thief. Then the heavens will pass away with a terrible noise, and everything in them will disappear in fire, and the earth and everything on it will be exposed to judgment.
References for 2 Peter 3:10