Dear Lysander,
I love all questions that start with "Can you show me where in the Scriptures it says ..." - this is how we should enter into dialogue with our brothers and sisters! If only we would learn to listen to the Word and put our own prejudices and pre-conceived ideas to one side and let it penetrate our hearts. I include myself in that; I want to open myself up to God's Word, under the guidance of the Holy Spirit of course, in order to be able to be continually learning, for "disciple" means "student" or "learner". How can I learn if I shut up my ears? Many times in the past I have shut up my ears, wanting to protect myself from false doctrine and "heresy", but I now realise that God will protect me as I investigate the Bible and other people's beliefs, if I "remain" in Christ (John 15:4).
To answer your question, chapter 18 of Revelation speaks of "The Fall of Babylon", which is generally understood by theologians and students of the Bible to represent false religion. We read in verse 8 that: "She will be completely consumed by fire, for the Lord God who judges her is mighty.” That is why we are urged and warned in verse 4 to “Come away from her, my people. Do not take part in her sins, or you will be punished with her."