a singular noun taking "the" for free

Hi,

I have two sentences below with the singular noun "community." Kindly tell me why the writer has "the" in front of it? I see a lot of singular nouns automatically have "the" in front of them in sentences without being subject to the usual rules of  specificity and prior precedents. Kindly tell me why they are so.

Ex.

1. ... presents Christ as an alternative to the non-believing military community.    

2. The event was well supported by the local community.

For your reference, a singular non is always singular and must have a word such as "a", "an", "the", or "my" in front of it.

Thank you. I think I heard from another Mr. Guru that specificity arises from the overall content of the writing, not to the specificity of a single element in the writing. Now I need your clear explanation on specificity regarding the placement of "the" in front of nouns.   

I'm not sure what you may mean by "the usual rules".

The word communities is a perfectly good word, so I don't see how it would be restricted to the singular.

In the singular, however, the only choices for an article are a or the.  Not having any article is not an option.

an alternative to a non-believing military community means that the author doesn't know which community or doesn't want to tell us which one or doesn't think it's important to tell us.  The reader is reasonably expected to ask "Which non-believing miliary community?  (of several)".
an alternative to the non-believing miliary community means that the author expects the reader to know exactly which community he is referring to.  In all probability he wants us to think the community consists of all military people who are not believers.

supported by a local community means supported by one of the communities in the vicinity (of the event), and the author does not think it is important to tell us exactly which one.  The reader could reasonably be expected to wonder which local community the author was referring to.
supported by the local community means supported by that community in the vicinity (of the event) which everybody knows about or can easily deduce.  The reader is not expected to ask which community if this wording is used.  The reader is expected to figure it out on his own.  Almost certainly, the author means the very community in which the event took place.

CJ

P.S.  Very briefly, the presence of "the" tells the reader (or listener):  Figure it out for yourself!  Something you know about this situation or other situations you've experienced in life or something I've written (or said) previously about it is enough so that you can figure out for yourself exactly what I'm referring to.