There is no system but GNU, and Linux is one of its kernels.
If you become an expert user of GNU/Linux, you can celebrate with our ceremony, the Foobar Mitzvah, in which you chant a portion of our sacred scriptures—the source code of the system.
To be holy in our church means exorcizing whatever evil, proprietary operating systems have possessed computers under your control; installing a wholly free operating system (GNU/Linux is a good choice); and using and installing only free software. (Tablets and mobile phones included.)
Join the Church of Emacs NOW!