Hi Richard. Thanks for inviting me to answer this question. Fun. :)
The way I understand Revelation 12:13, the word "They" is referring to those who beleve in Jesus Christ as the only begotten Son of God... (Christians). *If you look closely throughout the New Testament, Jesus Christ is called "The Lamb of God." *Christians are sanctified, meaning; to make holy, consecrate. To purify or free from sin through the blood of Christ, Him dying for us so we can live.. as He did, in order to glorify God.
Here, I understand Revelation 17:9 and 18:4 as God simply talking about the result of SIN. Those that turned their back on the Truth and followed the great seduction of satans world. Those who took no authority over all the temptations, who rationalized and fought for their own wisdom and power in this world far removed from God and the truth of His Son Jesus Christ. They obviously have no place with God, His Son, or His people do they.
I look forward to hearing from you again! -Asha