i'm not positive but i think it might be in revelations

In revelations, it says Jesus will make the armies of the beast into a lake of blood in Megido.

They say the image comes from Revelatins, but Revelations is just a vision, it is not Jesus. Matthew 7:22-23 on the other hand IS Jesus, and what he says of that day is worrying "Many will say to me in that day, Lord, Lord, have we not prophesied in thy name? and in thy name have cast out devils? and in thy name done many wonderful works? And then will I profess unto them, I never knew you: depart from me, ye that work iniquity." Now, it's obvious he won't be saying that to the Muslims or the Hindus or the Buddhists etc. So anyone caling themselves Christian needs to pay heed and make sure they ARE following what Christ is telling you in the Gospels and NOT what others say he told them to tell you. "and in secret have I said nothing." declared Jesus in John 18:20

They are ancient ideas. They have the flavour of the Old Testament which are a different group of gods altogether.

The Jewish idea of what their Messiah would be and what he would do is very different from the NT picture of the peace loving Son of God. . They were expecting a great warrior or general or leader that would end the Roman occupation of Israel and restore the kingdom of David. They weren't expecting and did not wish for somebody to 'take away the sins of the world'. They had no notion that the Messiah would be the Son of God - they didn't know God had a son. . The main reason why the Jews rejected Jesus was because he was not at all like the Messiah that they believed the scriptures (OT) promised.

Revelation 19:11-21 "Then I saw heaven opened, and behold, a white horse! The one sitting on it is called Faithful and True, and in righteousness he judges and makes war. 12 His eyes are like a flame of fire, and on his head are many diadems, and he has a name written that no one knows but himself. 13 He is clothed in a robe dipped in [4] blood, and the name by which he is called is The Word of God. 14 And the armies of heaven, arrayed in fine linen, white and pure, were following him on white horses. 15 From his mouth comes a sharp sword with which to strike down the nations, and he will rule them with a rod of iron. He will tread the winepress of the fury of the wrath of God the Almighty. 16 On his robe and on his thigh he has a name written, King of kings and Lord of lords. 17 Then I saw an angel standing in the sun, and with a loud voice he called to all the birds that fly directly overhead, “Come, gather for the great supper of God, 18 to eat the flesh of kings, the flesh of captains, the flesh of mighty men, the flesh of horses and their riders, and the flesh of all men, both free and slave, [5] both small and great.” 19 And I saw the beast and the kings of the earth with their armies gathered to make war against him who was sitting on the horse and against his army. 20 And the beast was captured, and with it the false prophet who in its presence [6] had done the signs by which he deceived those who had received the mark of the beast and those who worshiped its image. These two were thrown alive into the lake of fire that burns with sulfur. 21 And the rest were slain by the sword that came from the mouth of him who was sitting on the horse, and all the birds were gorged with their flesh." The Rider on the white horse is none other than Jesus Christ himself and when He comes back, He will take care of business.