here's a more accurate and comprehensive definition of the term atheism.

The term atheism is formed of the Greek prefix a- (meaning "without" or "not") and the Greek-derived theism, meaning a belief in a god or gods. The literal meaning of the term is therefore without a belief in a god or gods, making any person who does not believe in the existence of a god or gods an atheist -- including both those who assert that no gods exists and those who, for whatever reason, do not make any assertion regarding the existence of gods. In modern usage as reflected in most dictionaries, atheism is the assertion that no gods exists, or that the existence of gods has infinitesimal probability. Atheism is not synonymous with irreligion (Irreligion is the absence of religious following. Although people classified as irreligious do not follow a religion, it does not imply a lack of belief in a god or gods); the idea of an eternal non-created universe is an important concept in some religions and as such it is possible to be very religious and very atheistic.

On the merits of this app: quite entertaining, conversions are sometimes rather quirky, but all in all a pretty funny idea.