and upon her FOREHEAD a name was written, a mystery,
The devil has a need to know names. Without a name, it is difficult to recognize a person's accomplishments, to take credit, or to show pride. So it is not unusual for this woman to have a name on her forehead. Furthermore, at the time the Revelation was written, prostitutes wore a band around their forehead to indicate they were "available". So, too, this woman is saying to the earth, "I am here, choose me!" (Jeremiah 3:1-3-5)
There are two previous mysteries in Revelation: 1) "mystery of the seven stars" (Revelation 1:20) and 2) "mystery of God" (Revelation 10:7). Those two mysteries are good mysteries. This mystery is of the imitation church and also is "spiritual" in nature. A mystery is associated with any religion; for TRUE BELIEVERS, the mystery of Christ (Ephesians 3:1-4-13) and the mystery of the gospel (Ephesians 6:10-19-20). To the earth (and particularly those who took the mark of the beast), the religion of this harlot also is a mystery.
"BABYLON THE GREAT, THE MOTHER OF HARLOTS AND OF THE ABOMINATIONS OF THE EARTH."
Nimrod (name means 'the rebel') founded Babylon (Genesis 10:6-10-20) as the center of a cultist and idolatrous religion. Historians indicate that it was Nimrod's wife who championed this religion. Almost all religions that are against true God worship demonstrate some of the characteristics of that Babylonian religion. Throughout the Old Testament and even today, Jews have struggled to remain apart and untainted by the Babylonian influence.
Babylon = wicked woman (Zechariah 5:1-11).
Observation: A person sometimes hear Islamists use the phrase "the Mother of all ....". Here, this woman is MOTHER of many other HARLOTS. She also is "the Mother of the ABOMINATIONS". These are not localized to the Middle East but rather are "of the earth". Most likely the abominations are forms of evil and idolatry (Deuteronomy 7:17-25-26). At this point during the tribulation, the world will be practicing a unified religion that is evil to its core and centered around idolatry (Revelation 13:4,15).