Hi Pete
Many thanks for your reply - and I accept what you say. Regarding the seventh head on the beast, this was the historic Islamic Empire (or Caliphate), and the 42 months in Revelation 11:2 do indeed refer to the 1279 years from 688 A.D. to 1967. I have no problem with that, I have believed that for several years, and I still do.
The problem is that the 'beast from the sea' itself is the eighth anti-God entity (see Revelation 17:11), the resurrected Caliphate, the "image" or replication of the seventh head that appeared "as if it had been mortally wounded and his deadly wound was healed". Thus the 'beast from the sea' itself is the End-Times Caliphate that was spoken into being ("given breath") by the 'beast from the earth' (Abu Bakr al-Baghdadi) on 29th June 2014 - and there is absolutely no way that this eighth entity is going to continue for 1279 years!
Revelation 13:5 appears to me to refer to the 'beast from the sea' itself, the eighth entity, and not to one of its heads. Like you, I had originally thought that the 42 months in Revelation 13:5 were simply a reference to the 42 months in Revelation 11:2, representing the time period of 1279 years that the "seventh head" was given authority to establish Gentile control over the holy city of Jerusalem. However, on further reflection, the context of Revelation 13:5 (look back at verse 4) suggests that this verse appears to refer to the 'beast from the sea' itself, the eighth entity, and thus it refers to the resurrected Caliphate rather than to the original one.
Of course, Biblical prophecy is often multi-layered, and sometimes it has more than just one fulfillment. If you wish, therefore, we could say that Revelation 13:5 points both to the time-period of 1279 years that commenced when the "seventh head" was given authority and also to a time-period that is relevant to the End-Times Caliphate (the eighth entity). In respect of the End-Times Caliphate, the "42 months" cannot refer to 1279 years (far too long) and so this must have a different interpretation. Applying the "days for years" principle in respect of the "seventh head" time-period, but applying literal Biblical months in respect of the End-Times Caliphate, allows us to distinguish between the two.
The "days for years" principle is clearly a correct one, because the calculations involving this principle are too accurate to be just a coincidence. Likewise, I would contend that interpreting the "42 months" as literal Biblical months in respect of the End-Times Caliphate is also too precise to be just a coincidence.
Please note that I am only saying that authority was given to the End-Times Caliphate over a geographical area for 42 Biblical months (from 29th June 2014 to 19th November 2017). I am not saying that the 'beast from the earth' has met his end, because he has not. I am also not saying that all the followers or members of the 'beast from the sea' have died or gone away, because they have not. I am only saying that a 42-month allotted time-span for the 'beast from the sea' to control territory has expired - but the 'beast from the earth' and his followers will continue to do their worst until the very end. In particular, the "ten kings" who "receive authority for one hour as kings with the beast" still have their job to do in respect of the burning of 'Mystery Babylon'.
The reason that I posted my comments on the fulfillment of Revelation 13:5 is because I think that the fulfillment of this verse shows us how near to the very end of the age we are getting. I mean, what else is left to happen? With Revelation 13:5 fulfilled, we then move on to Revelation 14 - which gives us a sequence of events. Verse 6 tells us of the angel with the everlasting gospel. This angel has been giving dreams and visions to many people across the world already, and many Muslims in particular have come to faith in Jesus through dreams, visions and other supernatural occurrences - especially in countries like Iran - and there are millions of them (praise God!). Verse 8 tells us that "Babylon is fallen", after which we are warned that those who persist in worshipping the 'beast from the earth' (Abu Bakr al-Baghdadi) and his "image" (the Caliphate that he spoke into being as a replication of the original Islamic Empire, even though it no longer "has authority") shall indeed "drink of the wine of the wrath of God". Then, in verses 14 to 16, we can read that the faithful church is 'raptured'. All of this suggests to me that the only "big" event now remaining before the 'rapture' is the fall of 'Mystery Babylon' - and, once this occurs, Jesus will be getting in to the heavenly elevator to come down on the clouds for us. So, time is short! And I think I will stop there.