I started thinking about this a couple of years ago. What if the “false religion” of the Beast is not some perverted Christianity at all but, rather, is Islam.
Even Hal Lyndsey missed that back in the day.
Not saying it is, but it is an interesting thought.
The Koran is a perverted version of the Bible. So that part fits.
I highly recommend getting and reading the book(s) - however, if you want a free online early version, it is here:
http://www.answering-islam.org/Authors/JR/Future/index.htm