There's also a popular open source project which requires its contributors to be religious!

Was this a veiled reference to SQLite and their Rule of St. Benedict "Code of Ethics"? If so, I think a more relevant mention of SQLite's approach to FOSS would be that they are open -- public domain, even -- but tend to have a policy of accepting no contributions, in order to assure the public domain-ness of it all. I'm not aware of many projects that take such an explicit stance out of policy and not just laziness.