Read it all and consider the context, as well as the Gospels for more clarification.

First, the "restrainer" is removed that kept the "evil ones" from having complete and total control. The restrainer is the rapture. After the Church is raptured away, people will slowly start seeing what is happening for 3.5 years and convert, as the Christian population goes from 0 to "an innumerable mass". Out of that "innumerable mass" grows from people realizing what is really going on, the "One World Government" must eliminate those "religious nutjobs" and see them out trying to force them to renounce their beliefs. When they do not, they are executed as martyrs. At this point, one of the main goals of the "New World Order" will be to seek out and kill all the recent conversions, hence...drunk on the blood and so forth.

So, first their is a rapture and the Church is gone completely. Then people will start realizing what really happened and convert making a new Church of believers....then those believers will be hunted down and executed.