Revelation 20:7-10
7 Now when the thousand years have expired, Satan will be released from his prison 8 and will go out to deceive the nations which are in the four corners of the earth, Gog and Magog, to gather them together to battle, whose number is as the sand of the sea. 9 They went up on the breadth of the earth and surrounded the camp of the saints and the beloved city. And FIRE came down from God out of heaven and devoured them.
NKJV

Saint Augustine on Rev 20:7-10

The words, “And they went up on the breadth of the earth, and encompassed the camp of the saints and the beloved city,” do not mean that they have come, or shall come, to one place, as if the camp of the saints and the beloved city should be in some one place; for this camp is nothing else than the Church of Christ extending over the whole world. And consequently wherever the Church shall be,—and it shall be in all nations, as is signified by “the breadth of the earth,”—there also shall be the camp of the saints and the beloved city, and there it shall be encompassed by the savage persecution of all its enemies; for they too shall exist along with it in all nations,—that is, it shall be straitened, and hard pressed, and shut up in the straits of tribulation, but shall not desert its military duty, which is signified by the word “camp.”

The words, “And fire came down out of heaven and devoured them,” are not to be understood of the final punishment which shall be inflicted when it is said, “Depart from me, ye cursed, into everlasting fire;” (Matt 25:41), for then they shall be cast into the fire, not fire come down out of heaven upon them. In this place “fire out of heaven” is well understood of the firmness of the saints, wherewith they refuse to yield obedience to those who rage against them. For the firmament is “heaven,” by whose firmness these assailants shall be pained with blazing zeal, for they shall be impotent to draw away the saints to the party of Antichrist. This is the fire which shall devour them, and this is “from God;” for it is by God’s grace the saints become unconquerable, and so torment their enemies. For as in a good sense it is said, “The zeal of Thine house hath consumed me,” Ps. 119:9, so in a bad sense it is said, “Zeal hath possessed the uninstructed people, and now fire shall consume the enemies,” Isaiah 26:11. Saint Augustine's City of God and Christian Doctrine, pages 692-3

 

The "FIRE which came down from God out of heaven" was, once again, the Holy Spirit Himself as He moved through "the Reformers" whose ministry is commonly known as, "The fires of the Reformation" or simply, "Reformation fire." This Holy Ghost fire was the great rescue of true Christendom (Augustine's "City of God") which had become besieged by enemies on every side: militant physical enemies, (resurgent Islamists and atheists and the Golden Hordes of the Far East, et al), as well as ravenous ecclesiastical enemies (religious dictatorships of institutionalized heresy in high ecclesiastical office).

These Reformers, armed within by the Word of God and powered by the Spirit of God exherted ministerial powers that consumed the religious adversaries besieging the true Saints. The armies of Chrisenized nations found themselves invigorated to mount a successful resistance to the Islamic resurgence on the brink of breaking through to invade the Christian stronghold of Europe as they had done throughout Africa and Asia.  By their ministry, the fires of the Reformation, true believers in Christ & His simple Gospel exerted themselves anew to throw off the threats and retain the reign of the Saints granted them by God at Christ's Return around 70AD.  Three hundred years after the crowning of Hildebrandt as Pope (1073AD), John Wycliffe completed his doctorate in theology in 1373AD and began his ministry of reformation. John Wycliffe is lionized as, "The Morning Star of the Reformation."