And I saw the woman DRUNK WITH THE BLOOD of the saints,
Many churches/religions claim they have many moral virtues, but if they take the life from people (saints, witnesses of Jesus, or ordinary people), they are exposed as not being the TRUE church (Revelation 16:5-6)
It is this BLOOD which will be the evidence to seal the doom of the apostate church (woman/Babylon). This blood is the guilty verdict against them (Revelation 18:21-24).
Many scholars distinguish the use of 'saints' here to mean those people who stood for righteousness and fought against idolatry and evil prior to Christ. Recall that Babylon physically existed long before Christ (Hebrews 11:32-38).
and with the BLOOD of the witnesses of Jesus.
It is difficult to understand why the devil thinks he can destroy us by killing us. Apparently, he doesn't believe that the BLOOD of Jesus is an everlasting life event. Jesus knew, though, that the devil would try (Matthew 10:16-23).
The expression "drunk with the blood" has been used from old to mean "lust for violence". It is in this context, the expression is used here. Somehow, we, too, understand this through the use of words like "jihad", "holy war", etc.
And when I saw her, I WONDERED GREATLY.
The anti-TRUE church/religion thrives on murder and bloodshed. It is part of the "Babylonian" religious system to try to eliminate anyone who doesn't believe what they believe (whatever that may be). To think that was only in the past is faulty thinking. It still is going on today, and among liberal churches it includes abortions ..... how can a tiny heart in a fetus not be pumping the very BLOOD being talked about here?
Perhaps, what caused John to WONDER GREATLY was the duration and intensity of this DRUNKENNESS. While he personally grieved over the violent losses of fellow apostles, this must have been overwhelming to him when he saw this vision.
This verse concludes the vision (verses 1 - 6); the interpretation by the angel follows.