Emacs is written in Emacs LISP, which is its own language. The really performance-critical stuff is written in C, as is the interpreter, but that’s it.
I interpreted your comment to mean something like “Emacs is configurable with third-party LISP code”, in much the same way as Vim is configurable with third-party Vimscript.
But Vim is written in C, Vimscript being just a bolt on, whereas Emacs LISP is its own language entirely, a distinct variant of LISP, and much of Emacs implemented in it.
LISP is a family of languages (much like BASIC). So Emacs Lisp is still a LISP.
I don't even know why you're bring Vim into the discussion when it has nothing to do with the topic being discussed. It doesn't invalidate the statement I made; I just makes your reply look a little snobby because you seem concerned that someone might compare Emacs and Emacs Lisp to Vim and Vim Script (I clearly wasn't given the complete lack of reference to Vim in my post).
To be honest I thought we had gotten past those tedious flamewars in the 90s.
> "Emacs is a great OS, but it lacks a decent text editor."
The comment presumably made because emacs is extended with LISP.