L-ism is the Religion of L from Death Note, the best character ever. L is the genius in charge of the Kira case. A person who follows L-ism is and L-ist.
Rei: Why L-ism? Why L?
Akuma: ISN'T IT OBVIOUS? I mean... LOOK AT HIM!! He's a smarty mcsmart whose OBSESSED with sugar... AND HIS BIRTHDAY LANDS ON HALLOWEEN ~twitch~ he... is... god...
Kit: Dude, you are one extreme L-ist!
Narumi: FOR GOOD REASON! ALL HAIL L!!