Well, this is my private interpretation. The Fathers were not stumbling all over themselves to interpret Revelations, and I pretty much gave up studying the book after converting to Orthodoxy. So, there really is no Patristic backing for what I have to say.
I believe that the key to this verse is in the passages before it. I believe that this passage refers to the Antichrist, and that he will be given power to wage war against the Saints, and will overcome them (but not prevail against them). While I believe that Salvation is a process, I also believe that God, who knows everything, also knows who will be saved. And it is those names that are written in the "Book of Life". What this passage means is that the Antichrist will be universally worshiped, and this includes the Orthodox, who will apostatize. He will subdue the Church, just as the true Jewish Church was subdued during the time of the Great Prophet. However, like that time, there will be a remnant of people who will not bow their knee to the Antichrist, just like there was a large number (7000) in Israel that did not bow to Baal. These are those who's names are written in the book of life. While the Church will be overcome, and the visible Church will cease to exist, the Devil and the Antichrist will not prevail since the remnant will remain until Christ comes again. The remnant will be small since Jesus says "When I return, will I find Faith?"
This is just my opinion, for what it is worth.