Language-agnosticism and why is it called that

Language agnostic refers to aspects of programming that are independent of any specific programming language. At least, that's how I've heard it used for the last thirty years.

The word "agnostic" is derived from the ancient Greek for "don't know". So something which is "language agnostic" doesn't need to know about computer languages; it means the same thing as language independent. Things that would be language agnostic include algorithms, or Agile, or a runtime library with bindings to many languages.

Some Mac OS X features are not language agnostic, because they're really designed to be used from Objective C, can only be used with difficulty from C or C++, and don't even have bindings for many languages.

There can also be a subtext to using "language agnostic" rather than other terms.

In colloquial English, someone who says they're "agnostic" means they are neither religious nor an atheist: they "don't know" about God. This is usually verbal code for "I don't like to talk about religion, so don't try to convert me."

So sometimes when people talk about being "language agnostic", they're trying to stay out of arguments about what computer language is better.