Why will the world's armies fight against Jesus Christ as He returns in the sky? Because people on earth will think it is an invasion from space. And that's no joke.

We all have heard of the Second Coming of Jesus Christ. He will appear coming out of the heavens, riding on a white horse, and, his armies will be following Him riding on white horses also. And the armies of the world will unite and fight against him as He is coming out of the sky. We are told a little more about this in other areas of the Bible beside the book of Revelations.

Isaiah 66:15 For, behold, Jehovah will come with fire, and his chariots shall be like the whirlwind; to render his anger with fierceness, and his rebuke with flames of fire.
Revelations 19:14 And the armies which are in heaven followed him upon white horses, clothed in fine linen, white and pure.

The armies that follow Christ at his return, will be in Chariots, and, on Horses. Now, most of us would expect to see him coming out of the sky on a literal horse. But, in fact, He won't be on a literal horse. Why would the armies of the world go to war against someone coming out of the heavens on a horse? Because it's not going to be literal horses and chariots. We are told in Ezekiel a little about God's "Chariots" etc.

Eze 1:16 The appearance of the wheels and their work was like unto a beryl(Crystals which are different colors): and they four had one likeness; and their appearance and their work was as it were a wheel within a wheel.
Eze 1:17 When they went, they went in their four directions: they turned not when they went.
Eze 1:18 As for their rims (rings or curves), they were high and dreadful; and they four had their rims full of eyes round about.
Eze 1:19 And when the living creatures went, the wheels went beside them; and when the living creatures were lifted up from the earth, the wheels were lifted up.
Eze 1:20 Whithersoever the spirit was to go, they went; thither was the spirit to go: and the wheels were lifted up beside them; for the spirit of the living creature was in the wheels.

God's Chariots from this account are some kind of very bright, and, very powerful wheeled structures, and spirits are inside of the wheels and, when the spirits move, the wheels move. Why is this important to know? Because when He returns with His armies, they will be in Chariots like this, or, similar. Again, why is this important? Because the governments of the world will tell everyone that this is an invasion from space. They will tell everyone that, these are, in fact, UFO's. Which is precisely why, the armies of the world will go to war against these "things" coming down out of the sky. We have been programmed to believe (through movies and popular culture etc) that anything coming out of the sky as in UFO's, will be dangerous, and, act counter to our welfare. And, that is precisely why we have been told, (albeit informally via Hollywood etc) that anything "alien" from space is not good. Basically, we've been programmed to accept this.

Now, of course, these aren't just, "aliens." It will be Jesus Christ and his armies, riding on what the Bible tells us are "horses," and "chariots." All through the Bible, chariots are described as instruments of war etc., although, some prophecies that pertain to the future, as in, the time we live in now, also say that men will use chariots for war etc. But of course, we don't drive around in literal horse drawn "chariots" anymore. We drive around in mechanized vehicles. So, throughout Biblical prophecy, the words Chariots, and "Horses," are simply in reference to whatever mode of transportation the people of that time period are using. The same will be true for God's chariots, whatever they are, and, in whatever shape they show up in. These will be angels and saints riding on "Chariots" of fire etc., and, the world will be made to believe that it is an invasion of sorts, which is why the world will go to war against whatever is coming down out of the sky.

Here is the scripture reference to that war between mankind, and, God's angels, and, Jesus Christ himself.

Rev 19:11 And I saw the heaven opened; and behold, a white horse, and he that sat thereon called Faithful and True (Jesus Christ); and in righteousness he doth judge and make war.
Rev 19:14 And the armies which are in heaven followed him upon white horses, clothed in fine linen, white and pure.

Notice they are all on horses.

And here we have the armies of the world, going to war against Jesus Christ, and, his armies.

Rev 19:19 And I saw the beast, and the kings of the earth, and their armies, gathered together to make war against him that sat upon the horse, and against his army.

Now, armies don't go to war against something they can't see. Jesus and his armies (angels and saints) will be fully visible to everyone in the world. And, they will be coming down out of the heavens. Of course, you will be told that they are "aliens." But of course, it won't be "aliens" per-se. It's Jesus Christ. And the ending is VERY bad for the armies of the world. As we see, they are completely annihilated.

Rev 19:21 and the rest were killed with the sword of him that sat upon the horse, even the sword which came forth out of his mouth: and all the birds were filled with their flesh.

So, in the end, this will be one of the greatest deceptions of all times. The governments of the world will tell everyone that the returning Christ is in actuality an invasion from heaven, or, space if you will, and, the world's armies will gather to fight off the threat to the world. What in the world else would unite the armies of the world? Not much! In fact, probably nothing. And, you should expect to see this in your lifetime. Actually, it's probably not too far off. The world's fighter jets, and tanks, and ships will all fight against Him coming back, because, they will think it is someone else. And, the world's armies will be utterly and completely, wiped off the face of the planet. And a lot of people will die as a result of this "war" against Him.