Our Lord Jesus, by revelation from His God and our God, has left us in Revelation 13 a powerful sequel to the prophecy given to Daniel in Daniel 7. The angel showed Daniel that the lion in Daniel's prophetic vision was Babylon and the bear was to be Persia and the leopard was to be Greece so when God showed the future Beast empire as a mixture of leopard and the lion and the bear it is quite clear what this means. When the beast empire is shown coming out of the sea this too recalls the same detail in Daniel's prophecy of the lion, Babylon (Neo Babylonian empire led by Nebuchadnezzar), coming out the sea stirred up previously by the four winds of Heaven. The nations around the world were in turmoil as Nebuchadnezzar took power after decades of rebellions and scourges and city sackings all over the world (Scythians, Medes, Egyptians and the like all scourging the earth). In the Revelation vision it is a sea not said to be whipped up like this but with Satan as a dragon newly cast out from Heaven standing there on the shore of the sea. This Revelation beast combines those empires as one combined empire. The terrifying reality worse perhaps than the world-ending turmoil of the decades before Nebuchadnezzar's rise is that the dragon will be furious having been forced down to the earth out of heaven and will vent that fury like never before by how totally he gives his power to this new beast. When? Of course we do not know the timescale but to be sober about it, these empires of lion (Neo) Babylon and bear Media-Persia and leopard Macedon-Greece did not last much more than 50 to 100 years at their height with each having a few successive 'kings of kings' (Persia having four) with reigns of up to a few decades on average. Nor did the appear overnight but took a decade or two for the groundwork to be set down before they gained territory and took their first gains of conquest. So on one hand a brand new combination of such empires would take a decade or two to develop and could last fifty to a hundred years before being defeated at Christ's coming in power. We might have decades before a hint of such an empire's rise appears and that time could be greatly clouded and darkened for unbelievers by the horrendous apocalyptic events preceding it and Satan being cast to the earth from Heaven. Such events occurring along the lines of Revelation's first twelve chapters would enlighten believers who see their redemption drawing near. Revelation 11 is key to knowing whether its apocalyptic events are happening because there is clear reference to the literal city of Jerusalem ("where our Lord was crucified") and there is mention of a literal, physical temple there: It is at this time that the Beast Empire appears; when two martyrs it slays will rise from the dead in full view and ascend before an earthquake splits the city into three. It all seems literal in this passage. If this hasn't happened then the following chapters have yet to happen too. So since a literal, physical Jerusalem Temple is not built with Gentiles trampling its outer court like chapter 11 relates it is pretty clear we are not seeing yet the events of the following chapters and the Beast is still to arise as a world empire of the order of those ancient world empires. I reckon decades of Empire rule have not yet started and will not start until that Jerusalem Temple is built and we will see it rise when the two martyrs rise. The Beast is primarily a leopard. It has a lion's mouth and bear's feet but primarily it is like a leopard. The angel told Daniel (Daniel 7) the leopard is the empire of Greece. Look at how the original leopard grew. The Ancient Greek Empire took shape by alliances between cities (perhaps the leopard's spots?) that happened quickly led by one ruler Philip of Macedon and it may well be that the new Greece Empire will form as alliances are quickly made between cities while maybe Iran (the bear) and Iraq (the lion) are only joined with later. It might be like the first such empires where it took two or three reigns in succession to fully form as other empires are either conquered or united through alliances and marriages by these successive rulers. It might be the leopard's first powerful rising ruler forms alliances as before then fights major battles and later successors bring in the lion as head and the bear as feet. All over decades like before. An indicator it is happening is Rev 11 where there is rule over Israel and Jerusalem has a Temple. Revelation is what Christ says so this applies: (2 John verse 9) "Anyone who runs ahead and does not continue in the teaching of Christ does not have God; whoever continues in the teaching has both the Father and the Son." We have to keep reigning in our thoughts and keeping them if they are in line with the teachings of Christ (and the revelation of Him within us and hope of future revelations of Him) and dropping them when they are contrary. (1 Peter 1:13-15: " Wherefore having girded up the loins of your mind, being sober, hope perfectly upon the grace that is being brought to you in the revelation of Jesus Christ, as obedient children, not fashioning yourselves to the former desires in your ignorance, but according as He who did call you holy, ye also, become holy in all behaviour,") So this Beast will arise when Jerusalem has a Temple and the Beast will reach a pinacle of power where for a short time it has power of all the world. How long it takes to reach this maturity might, I think, be similar to the time the original beasts of Neo Babylon onwards took which was rapid at first but prolonged over decades to reach full power. But what will happen between now and then to indicate the approach of it? I think it is still to come the revelation in Revelation 9. A third of all mankind being killed by forces of evil originating at the Euphrates with the loosing of powerful spirits bound there. Maybe we have it beginning with the Iraq violence we see but it will grow, it seems to be saying, until it affects the whole world enough to kill a third of it - billions. Evil apocalyptic torments will lead up to this but maybe then there will be a high chance of not surviving to see the awful rise of the Beast. Maybe this violence will be the Armageddon foretold by Enoch and Ezekiel. When the third of trees and of all grass on earth gets burned up we will know it is starting soon because of what is written in chapter 8. Maybe Islam is merely incidental and maybe democracy is more characterstic since the beast is like a leopard (like the Ancient Greece Empire) but only has mouth like lion and feet like bear (Iraq and Iran). The leopard seems the main component and with dragon's power (Satan). I think what we see in present IS is a hint at the dragon power it will have but we are not at a stage of seeing it yet but some components might be forming decades before the full manifestation. What we see is chaos and enmity against Israel so this might be chapter 9 prerequisites forming which might put us before chapter 8 or at its start with the four angels at the Euphrates about to be released after a period of natural massive catastrophes some in answer to the prayers of the people of God (chapter 8 beginning). Out of it chapter 9 will grow and might result in Armageddon enemies of Israel attacking but Ezekiel 38 fulfilled with their demise preparing a way for Temple to be built as Jerusalem is strengthened by victory from God, preparing way for chapter 11. So I would conclude Islamic enemies of Israel supported by Russia as in Ezekiel 38 could rise up led by the four spirits released at the Euphrates (after a period of huge disasters burning up trees and grass - sun turning dark in smoke of it - like Joel 2) but war heightened in Megiddo (Enoch and Ezekiel) and all these turned on eachother to their destruction and leaving Israel to rise and Jerusalem to be dominant with a Temple but still so corrupt that saints try to flee it in adversity hence called Egypt spiritually in Rev 11. By this time the Beast will have risen with Satan empowering it so it kills the two witnesses in Jerusalem.
I tend to think the sixth seal is probably to haapen next and soon: Sun turning to sackcloth because of some massive apocalyptic event (Rev 6). Then perhaps soon after that (after a pause with protective spiritual sealing of the saints) the next seal (seventh, Rev 8) being a burning up of the third of the trees and all of the grass. So the Beast might be forming at early stages but it might be some time before it has its time of power (Rev 11 and 13).
