The background was complete with creatures that looked like versions of Baphomet. Was she truly, knowingly worshiping Satan or just using satanic/witchcraft symbolism as a calculated marketing strategy to create a buzz and sell records? In one sense it doesn't matter. Whether wittingly or unwittingly Satan was promoted and celebrated. Occultic imagery flashed on to many screens. I don't know if Katy Perry, a former Christian, even believes in Satan but the devil certainly believes in himself.
The Apostle Paul instructed Pastor Timothy to show mercy to those opposing his ministry:
Have nothing to do with foolish, ignorant controversies; you know that they breed quarrels. And the Lord's servant must not be quarrelsome but kind to everyone, able to teach, patiently enduring evil, correcting his opponents with gentleness. God may perhaps grant them repentance leading to a knowledge of the truth, and they may come to their senses and escape from the snare of the devil, after being captured by him to do his will. (2 Timothy 2:23-26 ESV)From this passage we see that people unwittingly can advance the devil's interest and agenda without even realizing it. This is true of many sorry souls who behave as Perry behaved onscreen. They may be active participants or "useful idiots" (to use the political term) but they surely are dupes.
Pray for Katy Perry.