Rev 17:5 says the mystery was written on her forehead. Jeremiah tells us in 3:1-5 where God prophecies of Israel pretty descriptively:
God says, If a husband divorces his wife And she goes from him And belongs to another man, Will he still return to her? Will not that land be completely polluted?But you are a harlot with many lovers; Yet you turn to Me, declares the Lord.
2 Lift up your eyes to the bare heights and see; Where have you not been violated? By the roads you have sat for them Like an Arab in the desert,
And you have polluted a land With your harlotry and with your wickedness.
3 Therefore the showers have been withheld, And there has been no spring rain. Yet you had a harlots forehead; You refused to be ashamed.
4 Have you not just now called to Me, My Father, You are the friend of my youth?
5 Will He be angry forever? Will He be indignant to the end? Behold, you have spoken And have done evil things, And you have had your way.