Any person who's studied literature for more than a year can tell you that the bible is incredibly important to British and American literature. Try reading a book that doesn't make an allusion to the bible, or contain some sort of biblical imagery. The Bible may be overrated but it's not so much a novel as it is the basis (and perhaps a substantial reference) to all of modern literature.
Also I definitely support Mocking Bird over The Scarlet Letter.
The most overrated books probably include Secret Life of Bees, The Da Vinci Code, and Wurthering Heights. These are all critically revered books that I just think are so fucking awful, cliche for the first two and if you think Mocking Bird and Scarlet Letter are boring, Wurthering heights would make you tear your eyes out