Revelation 11, is showing the biggest religions is what you don't want to be apart of at this point.
[link to www.adherents.com]

The two witnesses are witnessing against those because what comes first is the falling away first, before the truth returns.

The two witnesses are located at:

Revelation 11:8 And their dead bodies will lie in the street of the great city which spiritually is called Sodom and Egypt, where also our Lord was crucified.9 Then those from the peoples, tribes, tongues, and nations will see their dead bodies three-and-a-half days, and not allow[d] their dead bodies to be put into graves.


There's two witnesses and two places that describe the great city..Sodom and Egypt...

Let's look at Egypt and what happened there: Exodus 11

Let's look at Sodom and what happened there: Genesis 19