What is the rule of thumb, or formula, that publishers (publishing
companies) of Christian non-fiction books use to calculate things such
as marketing dollars to spend, advances to pay authors, royalty rates,
etc.  In other words, I've heard directly from a publisher that
publishers have formula or ratio, they use to determine how much
marketing dollars will be spent. It includes projected sales and some
other factors.  

Ultimately, I am trying to discover what a mid-level
author can expect in terms of marketing support for a new book (how
much a publisher is going to get behind this project), and given such,
what would reasonable advances and or royalties be for such a project.

I'm NOT looking for general industry standards from all of book
publishing. I want a response as it relates to the Christian
non-fiction segment of publishing. Any previous examples of mid level
authors on the rise would be excellent and tipped appropriately.
Comparative names include authors such as Jennifer Rothschild, Lisa
Whelchel, Elizabeth George, Tammy Trent, Sheila
Walsh, Angela Thomas.

So in sum, there are two parts to the question, though they may be related.
1. Is there a formula publishers use to determine marketing dollars
and support for a new book within the genre specified above.
2. What is a reasonable advance and royalty rate for an mid-level
author with a previous sales history of 75,000 units of previous book.

There is no formula, unfotunately there are a lot of publisher out
there taking advantage of authors.  From my research
http://www.christianpublish.com offers the same distribution and
quality of publishing Christian books at the most affordable rate
compared to others.  Make sure you check everything with some of the
other Christian Publsihing Companies. Some charge to high of a retail
price for the books.  Others charge a huge set up fee.  When it all
averages out you should receive royalty checks between 20-30% of
wholesale.

I am an author of several Christian nonfiction books, though none of
my books have sold 75,000 copies.  As a general rule, I think the
advance a mid-level Christian publisher offers reflects the amount of
royalties they expect the book to earn in its first year.  Various
factors can influence this.  If there is competition for the
manuscript, they may go higher than this.  If the book is considered
risky, they may estimate conservatively.  (Two-thirds of Christian
books lose money for the publishers.)

I have not had a contract in which the publisher committed a certain
number of marketing dollars to one of my books, but for authors in
demand, such a clause in the contract can be negotiated.  I have found
it valuable to develop a marketing strategy document for my books
prior to release and to make a trip to the publisher and request to
meet with the people who will be engaged in marketing the book.  I
hand out the marketing strategy piece I've developed and in 30 minutes
help them understand the nature of the book, it's intended audience,
and the book's selling points.  These marketing people have always
appreciated this, and it makes my book stand out in their minds from
all the hundreds of other titles they are publishing that year.

The royalty rate mentioned by the previous commenter sounds high to
me.  Most contracts have an ascending royalty rate--a certain rate for
the first 10,000 copies sold (for example), and then it increases
after that.  There may be three levels to the royalty rate.  I think
most of my contracts start at 14% of wholesale and then go up to 17%. 
Of course, to a degree rates are negotiable.  The more you do to
market your own work, the more attractive you become to a publisher as
an author.  I sell my books through my web site, to clients in the
course of my work, and through selling excerpts from the book as
articles to magazines.  (I have my contracts set up so that I keep
these reprint fees rather than having to split them with the
publisher.)