Atwood's work is often categorized as "speculative fiction". Take a look at how the term is used, especially by those in the "business":
What is Speculative Fiction? from Green Tentacles
What is Speculative Fiction? from Lost Books
From Atwood herself at Wired
You'll find Atwood's The Handmaid's Tale on this historical list-in-progress of dystopian literature at Wikipedia.
Atwood interviewed on religion by Bill Moyers via YouTube.