In Mark 13, Jesus reveals a whole list of things—shocking and fear inspiring things like wars, natural disasters and famines—that are NOT a sign of “The End.” He knew what He was doing too, because that is exactly what people start to think when bad things happen. Even followers of Jesus who read their Bible. They always seem to forget this passage. They see everything as a sign.
Included in the discourse about all the things that are NOT a sign of “The End,” but rather the normal course of the world and reality for His followers, Jesus talks about persecution and the related task of the declaration of the Gospel. He declares that the Gospel of the Kingdom of God will be proclaimed to all nations. This too is simply a statement about something that will occur, not a sign of “The End.”
What He also does not say here is that this is a triggering mechanism for “The End.” But that is what a lot of people try to make this statement mean. Even worse, they see it as a way to manipulate God. (But they don’t likely realize that is what they are doing.) Their thought is that they can make Jesus return—they can trigger “The End”—by accomplishing this task.
Now, our job is indeed to proclaim the Gospel. Even to do so to “all nations” whatever that means. But we are simply to tell. To everyone. It is God that orchestrates the way in which “all nations” are reached. It is He that determines what and when that is. People who put too much effort in defining “all nations” and strategizing the way that those nations can be ticked off some all-comprehensive list are in danger of missing the “trees for the forest” to reverse a cliché.
And there is a possibility that the Gospel will be proclaimed to “all nations” and “The End” won’t come just yet. Just as wars and earthquakes and famines will all repeatedly occur without Jesus coming back, it just may be that the Gospel will be proclaimed to “all nations” multiple times before “The End.” Some would say that it even happened within the time covered by Scripture in Acts chapter 2.
The sign you are looking for if you insist on a sign is Jesus coming in the clouds. If you see that happen, you are pretty safe in thinking “The End” has come!