Creed has only been legally interpreted as religion—and doesn’t pertain in a roommate situation anyway.
It depends on the locale, and I’m not saying I agree with it, but you might want to reconsider your view on the law. A roommate situation does not create a blanket permission to “discriminate.”
https://www.chicagotribune.com/news/ct-xpm-1997-05-22-9705230273-story.html