Articles - when the rules cease to apply

English as a Second Language English Vocabulary, Grammar and Idioms
1

Long story short - I’m working on a translation of the (or should I say “a”? It’s their only offer for the ongoing year) 2011 offer for a certain company and articles-concerned doubts just keep coming up. Sadly, all I can find on the Internet is that “you use the when you mean something specific and a/an when you don’t etc. etc.”.

“estimates of (the?) gas prices in a certain country till 2020”

What do I do about that? Gas prices should not be specific but here we’ve got all (the?) gas prices for the next nine years.

Also, by the way, what’s the rule behind “faith”? How is it that I came across “Puritan faith” but “the Christian faith”? Anybody?

2

“estimates of (the?) gas prices in a certain country till 2020” What do I do about that?– With plural nouns you can often omit the article. I would here.

Also, by the way, what’s the rule behind “faith”? How is it that I came across “Puritan faith” but “the Christian faith”? Anybody? – You can talk about the uncountable human capacity or you can talk about a specific religion; ‘faith’ carries both meanings.