To try to breathe some life into the debate, note that the first definition does not necessarily require the supernatural: a set of beliefs concerning the cause, nature, and purpose of the universe, especially when considered as the creation of a superhuman agency or agencies
[my emphasis]
It certainly leans strongly toward gods being necessary for a religion, but not exclusively. This would give Freodin a chance to look at the first half of the definition. For instance, do secular humanists have a set of beliefs concerning the purpose of the universe?
A quick look through the Humanist Manifesto shows a lot of interest in what the purpose of people or society is, but nothing at all about the purpose of the universe.