That's correct, the meme is referring to the Roman Catholic Church. Catholics use the word "orthodox" all the time – referring to orthodoxy as such, not Eastern Orthodoxy. I don't believe East Orthodox Christians use the term "Magisterium" but I'm not as knowledgeable about Eastern Christianity so I'm not positive about that.

Carlin's original bit was, "Have you ever noticed that anyone who's driving slower than you is an idiot,
and anyone driving faster than you is a maniac!?...There's certainly no one driving at MY speed!"