What is a religion?

What is a religion?
Religion is defined as the following

(a) The belief in and reverence for a supernatural power or powers regarded as creator and governor of the universe.
(b) A personal or institutionalized system grounded in such belief and worship.


Some theists claim that Atheism is just another religion, but based on this definition, Atheism is simply the lack of a belief or reverence for a supernatural power or powers. As such Atheism does not qualify to be referred to as a religion.