The full name of the document is Last Will and Testament. One definition:
A document in which a person specifies the method to be applied in the management and distribution of his estate after his death.
Will is a common term to refer to this document. I wouldn't call it informal; I think it's what people use most of the time. In a legal context you're probably better off using the full name, though.
I can straighten this out. And there's a funny little twist at the end.
The article is Richard Dawkins doesn’t deserve this fellow atheist’s smears:
John Gray should attack his ideas, not his character. (Coyne, Oct. 2014, New Statesman). There are three people connected to this article:
Jerry Coyne, the author, is an atheist, a contributing writer for New Statesman, a book writer, and a (not-so-lowly) biologist.
John Gray is an atheist, the Lead Book Reviewer for New Statesman, a book writer, and a philosopher.
Richard Dawkins is an atheist, a regular columnist and Dec 2011 Guest Editor for New Statesman, a book writer, and an evolutionary biologist.
Did I mention that all of them are atheists, have financial ties to the New Statesman, and are book writers? Just wanted to make sure you got that, in case you didn't. Good.
So Dawkins writes a book--a memoir actually. Gray bashes Dawkins in a New Republic article (which is published two days later in New Statesman). And in the New Statesman article you reference, Coyne bashes Gray for bashing Dawkins. Got it? Just wanted to make sure...
You see, Gray doesn't like the kind of atheist that Dawkins is, because Dawkins is politically against organized religion, while Gray is a let's-all-be-friends-and-tolerant-with-religious-folk atheist. And Coyne doesn't like Gray because he's bashing his friend, Dawkins, and he's saying, "No need to get all testy, attack ideas, not character." And Coyne also doesn't like the kind of atheist that Gray is, because Gray is a let's-all-be-friends-and-tolerant-with-religious-folk atheist.
So Coyne calls Gray a FAITH-eist! BOOYAH! MAJOR ATHEIST INSIDE-JOKE SLAM-DUNK PUT DOWN! "You're not a REAL atheist! You're a FAITH-eist!"
Now we can all laugh. HAHAHAHAHAHAHA!
Which is exactly the definition you referenced on Wiktionary:
It's a derogatory term that "radical" atheists can use to put-down "moderate" atheists. I doubt that anyone would call theirself a faithiest today (but it just might catch on as a non-derogatory term!) But Coyne is being hypocritical in using this term because he is attacking Gray's character while criticizing Gray for making character attacks!
Coyne makes another character attack. There's an idiom "get your facts straight" that Coyne could have said to Gray to admonish him for saying something counterfactual. But Coyne says "get your story straight" which is an idiomatic accusation that Gray is lying. (A "story" can be something "made up" which can be "a lie".) While the semantic context makes it clear that Coyne found a factual fault, the idiom pulls the meaning toward the lying connotation. So again, Coyne is employing a (subtle) character attack.
Personally, I think if one were to dig a little deeper, one might be able to figure out some type of connection between all these guys to show it's just a big money game to increase book and magazine sales.
Best Answer
I don't know the series, and it is possible there is something in the story that it is referring to. But my guess is that it means "If you follow me, you are going to need some expensive surgery to the part of your body that urologists treat".