Horse 1872 - Is IS A Country?

I want to set aside the murderous and barbarous nature of the Islamic State (IS) for the moment and attempt to answer a question set for me via email; that question is: "Is IS a country?"
The problem with very small questions is that there are often so few parameters to define the question properly, as to render it useless.

With only four words in this question, two of those being particles and one being the subject, the last word in the question, "country" is so hard to define that depending on who you ask, you'll even get different numbers of how many countries there are in the world. These numbers vary from 193 to a shade over 200, depending on how country-like a country is and who thinks that a given country is a country.
Do you include Macau, Hong Kong and Taipei as countries? Macau and Hong Kong are part of China but kind of not China and to further complicate the matter, both of them sent teams to the 2008 Beijing Olympics; which sounds really strange because that might be like Scotland or Nebraska going to the Olympics. Chinese Taipei thinks of itself as a country and most other places think of it as a country, even though China doesn't officially think that it exists.
Do you include Somaliland as country which is pretty well much independent from Somalia? Maybe? Should to include the Vatican City which issues its own currency, passports and what not, even though it might be part of Rome. By most accounts, the Vatican City is a country; whereas a places like Kosovo and South Ossetia aren't (but should they be?)

If the world can't settle on what is a working definition of what a country is, then maybe we could look at what country like aspects IS has and that might be a good way to answer the question.
In their favour, IS has established the rule of law of sorts within the territory it controls, in some places it has undertaken civil infrastructure repair by fixing roads and electricity lines. In that respect, IS is more country like than many places in Syria under Assad. Most visibly, IS maintains a military; which is currently causing the world so much strife.
This then is similar to the United States. At what point exactly was the United States a country? Officially it's taken to be the 4th of July, 1776, but was the place markedly different from the week before on the 27th of June, 1776? Since the actual declaration of independence was never circulated to the British, they wouldn't have said that the United States was a country, even a week later on the 11th of July, 1776. IS might very well argue that they already are a separate state (the name's even in the title: "Islamic State") and they're already fighting in that capacity.

If the measure of how country-like a country is is the indicator of if a country is a country, then this might include membership status to various international organisations. I don't think that North Korea is a member of the United Nations even though it is most definitely a country and we again return to Macau and Hong Kong at the Olympics. IS isn't a member of any international organisation as far as I'm aware but it probably wouldn't be allowed to join anyway. I don't know if not being a member of international organisations makes IS not a country because then you need to look at South Africa, Zimbabwe and Fiji which have all at various times been kicked out of the Commonwealth of Nations; that seems to be more dependent on whether other countries think that a thing is a country or not. I refer you to the United States in that summer fortnight in 1776.

Not even the idea of a defined border helps to determine whether or not something is a country or not. Granted that the idea of marking off territory by the use of landmarks and boundary stones is ancient, and there are some very famous walls and dykes which mark where a country ends but what happens in the case when these borders are nebulous or under dispute? Does a country cease to be a country if it can't define where it is? Does a country become a country if it wants to define where it is? IS currently has borders to the territory that it holds which are both nebulous and under dispute.

Frank Zappa once famously said that: "You can't be a real country unless you have a beer and an airline. It helps if you have some kind of a football team, or some nuclear weapons, but at the very least you need a beer." 
I kind of like that except that it excludes countries which officially oppose alcohol and there quite a few of those. I think that it would be handy if a country had at least a national sporting team of some sort (though that might make the West Indies a country and the Vatican City not a country), a national anthem, its own currency and postage stamps, a national flag, and at least one chain of shops which are unique to it. When in another country, one of the things that makes it feel like another country, is to be able to walk into a shop which is nowhere else in the world. I don't think that IS has its own currency or postage stamps and as far as I'm aware, there are no shops which are unique to IS.

On balance, I don't think that IS is a country and given their murderous and barbarous method of operation, I hope that they don't become a country either. Being afforded the title of a country, implies a sort of legitimacy and a right to govern; I don't think that IS has either of those things.