If you take a closer look at this battle description you will understand whom the Mahdi will appear amongst and why. The interesting thing to draw from this is that the kings of the world will fight against the rule of GOD on earth? what dose that tell you?

(Psalm 2:2) The battle of Armageddon will bring human rulership to an end.—Daniel 2:44.

,” “the kings of the entire inhabited earth” will be gathered “together to the war of the great day of God the Almighty.”—Revelation 16:14.

I saw heaven opened, and look! a white horse.+ And the one seated on it is called Faithful+ and True,+ and he judges and carries on war in righteousness.+ 12 His eyes are a fiery flame,+ and on his head are many diadems.* He has a name written that no one knows but he himself, 13 and he is clothed with an outer garment stained* with blood, and he is called by the name The Word+ of God. 14 Also, the armies in heaven were following him on white horses, and they were clothed in white, clean, fine linen. 15 And out of his mouth protrudes a sharp, long sword+ with which to strike the nations, and he will shepherd them with a rod of iron.+ Moreover, he treads the winepress of the fury of the wrath of God the Almighty.+ 16 On his outer garment, yes, on his thigh, he has a name written, King of kings and Lord of lords.+ (Revelation 19:11-16, 19-21)

19 And I saw the wild beast and the kings of the earth and their armies gathered together to wage war against the one seated on the horse and against his army.+20 And the wild beast was caught, and along with it the false prophet+ that performed in front of it the signs with which he misled those who received the mark of the wild beast+ and those who worship its image.+While still alive, they both were hurled into the fiery lake that burns with sulfur.+21 But the rest were killed off with the long sword that proceeded out of the mouth of the one seated on the horse.+ And all the birds were filled with their flesh.+ (Revelation 19:11-16, 19-21)

The one on the White horse could be hinting at Mahdi and the wild beast as Dajjal.

for then there will be great tribulation+ such as has not occurred since the world’s beginning until now, no, nor will occur again.+

For just as the days of Noah were,+ so the presence* of the Son of man will be.+38 For as they were in those days before the Flood, eating and drinking, men marrying and women being given in marriage, until the day that Noah entered into the ark,+39 and they took no note until the Flood came and swept them all away,+ so the presence of the Son of man will be.
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Our current generation of people in the end times remind about the people of NOAH. We have most similarities with the people of Noah. Gog and magog will serve as the flood. But he believers will inherit earth when the disbelievers are completely destroyed and deleted from earth in every single country except the believers you were with Mahdi and Isa banu Maryam will start new dawn of civilization on earth.

The kings of the earth take their standAnd high officials gather together* as one+Against Jehovah and against his anointed one.*+

If you see how the current picture of the world is shaped. Mankind is ever eager to Demolish ''SHARIAH LAW'' There nobody else campaigning for GOD's rule on earth except these who sincerely want to etbhlish the Law of God on earth. There is only one group and every nation and people are against them. Media and everything. The kings of the world are united against them basically and this are the people whom both Mahdi and Isa Banu maryam arrive amongst. If you were ever in the sense of your local muslim gov't or anyone else being righteous you were being deluded. They are secular people at best. They serve nobody except themselves.