Lisp is not only where functional programming originated, but also object-based programming leading to OOP. Lisp was the first language which had first-class objects: encapsulated identities operated upon by functions, and having a type.
For instance, an object of CONS type could only be accessed by the "getter" functions CAR and CDR which take a reference to the object, and by the "setters" RPLACA an RPLACD.
Meanwhile, the other higher level programming language in existence, Fortran, had just procedures acting on global variables.
There are other places in the Lambda papers and whatnot where they talk about objects, but I don't recall seeing that exact phrase. Of course, just what they meant by it is another question.