It’s funny how most people expect the world to end, at some point, in some way. The Pharisees knew from the Old Testament that God would judge the whole earth one day, so some of them asked Jesus what they should look for to see it coming ahead of time. In typical Jesus fashion, He lets them know that even the premise of the question is wrong. They were expecting the Messiah would arrive to set up God’s kingdom on earth (and He will), but Jesus tells them the kingdom of God is already present.
He repeats the warning to His disciples against following anyone who says, “Look, here!” for either the Messiah or the kingdom of God. Just as the kingdom of God is already among men and we don’t have to go anywhere in particular to see it, when Jesus returns to the earth, He will be visible to everyone at once somehow, and no one will have to announce His presence to anyone else.
His return will come suddenly, because people will be going about their day-to-day lives, just like they did before the Flood and the destruction of Sodom and Gomorrah. I had written “without warning”, but that’s not actually true. The Bible is full of warnings of God’s wrath being poured out on sinners. Heed the warning, trust in Jesus, and be saved! Asking for a sign to know when the day of judgement is coming is like asking when the inspector will arrive so you can procrastinate cleaning up. The point is not to get things ready at the last minute, but to be ready all the time. Noah and Lot were just as sinful as their neighbors. They weren’t rescued because they were good on their own, but because they loved the Lord and He made them righteous.
Make us ready, Lord, so that we may be found blameless upon Your return.