Can a personally legally worship another person in the USA?

A close friend of mine has a admirer that borderlines on the line between admirer and stalker. Lately this girl says she worships my friend, is planning a temple and a statue, and is spreading her faith to other people to get converts. My friend is really spooked out and said she wants to sue to her. However in the United States, I know we have freedom of religion. So does this mean the stalker/admirer can legally worship my friend or is this a special case that is illegal?