You’re off to a good start, religion is prominent and important topic covered in The Year of the Flood.
Buuut, you want to develop a clear argument about why it is important that Atwood focuses on it and how this interacts with modern society.
Think about the major points on religion she is making in the text and pull quotes about them.
Find some current, reliable sources that cover these major issues.
Then put them both together and your paper will be good to go.