It was, but isn t now, and any laws regarding it still on the books aren t really enforceable.
Michigan did have a law, passed in 1897, which made it a misdemeanor to use indecent, immoral, vulgar or insulting language in the presence or hearing of women or children. A canoeist, after having fallen in the Rifle River, was convicted of violating that law in August of 1998. An appeal of that conviction led to the Michigan Court of Appeals ruling that said law was unconstitutional in 2002. It was officially repealed by Michigan s legislature in 2016, as part of a legislative initiative to clear several outdated laws from its books. However, in 2003 Gerald Henning, an elderly corn and soybean farmer in Hudson Township, Lenewee County, MI, was charged with violating a similar law prohibiting vulgar and offensive language on a telephone. The charge was dismissed by a Circuit Court judge in Lansing, MI, in 2004, as it was similarly found to be an unconstitutional suppression of freedom of speech as protected by the first Amendment to the U.S. Constitution.
There is a state law prohibiting blasphemy which remains on the books, but it likely also isn t enforceable, for the same reasons as given above.
(Note: I am not a lawyer.)