Continued from previous verse.
19:2
for true and just are his judgments.
He has condemned the great prostitute
who corrupted the earth by her adulteries.
He has avenged on her the blood of his servants.”
This is the third time we hear that HIS JUDGMENTS are TRUE and RIGHTEOUS (Revelation 15:3 and Revelation 16:7 are the other two times). When something is repeated for three times in Revelation, the statement is to be considered of high importance. TRUE and RIGHTEOUS are requirements to be able to JUDGE. Thus, these JUDGMENTS can only be GOD's JUDGMENTS. We, even as redeemed believers, do not qualify yet (Luke 22:19-30).
He has condemned the great prostitute
God certainly doesn't consider the PROSTITUTE to be GREAT; only GOD is GREAT. Thus this verse is for human consumption. Humans have a tendency to idolize people they "look up to"; or those who have wealth or political power or religious stature; or themselves. Many so-called Christians succumb to this temptation. They have become corrupted with her IMMORALITY. They have rationalized their "Christian" status with their desired social status even after being specifically command to get away from the PROSTITUTE (Revelation 18:4-5). So strong is the corruption that many times "Christians" don't even recognize it or take steps to remove themselves.
An aside note, most of the Bible truly is about and for Abraham's descendants. But here "corrupting the earth" makes the JUDGMENT for all mankind.
Here we finally have the answer to the martyr's request in Revelation 6:10. The list of those avenged is given in Revelation 18:24.
For a brief discussion on a SERVANT, please refer to Revelation 1:1 verse discussion.