Let me give you one particular example of a “Signs in the Heavens” that would be “absolutely unique” and one that I do expect to happen.
That “sign in the Heavens” would be the Rapture. That’s going to be a unique event. Now, keep in mind that Jesus was “raptured” to Heaven, too. We have an “example” from Jesus of how that particular “Rapture” happened.
Over 500 witnesses stood there watching as Jesus was taken up into Heaven. They just stood and gazed and gazed. It would be my contention that the same kind of Rapture will happen for believers, too and that the world will see this “sign in the Heavens”... :-)
Keep in mind that the Bible does not say that we will be taken up “in an instant” but rather that we will be “changed” in an instant. There’s a difference and the *example* we have of the Rapture is that it’s something that happens that people “can see” happening...
That would definitely be a “sign in the Heavens” that would be absolutely unique.
ANOTHER SIGN in the Heavens that would be absolutely unique would be the angel that is sent around the world declaring the “everlasting gospel” to every nation, peoples, kinds and groups and tribes, etc. In other words, the Gospel of Jesus Christ will *finally* be given to all people in the world, when this angels is sent around the world with the Gospel. This is what *finally* accomplishes it.
And *that* would be another “unique” sign in the Heavens that has not been done before.
So, I’ve given you two possible “Signs in the Heavens” which meet that criteria that I’m talking about... :-)
We are certainly close to The Gospel being given to every nation, language group, tribe.