(BTW - I'd really like to hear from PastorDan and Ihlin on this).
Having read a number of the Diaries on the subject of more "Faith" language in our party, I've noted that the arguments are waaaay too simplistic. Like most things, everyone has lumped the latest fad, "Evangelicals", into a generic for all categories. It doesn't work that way, and without being careful you'll end up alienating part of the "faith" community by pandering to evangelicals.
Having been raised a Roman Catholic (albeit I'm now Agnostic) of Eastern European decent (the bulk of US Roman Catholics), I can tell you that the majority of Catholics share the "flinty New Englander" attitude. My very Catholic Mom and Grandmother used terms like "holy roller" or "Elmer Gantry" in a very disparaging way about anyone, including few other Catholics, that wore their faith on their sleeve. Most Catholics find public displays of religion to be rude and unseemly...and common to hypocrites.
Opus Dei? Forget about it. In the immortal words of a Jesuit I knew, "Why don't those jerks just become Protestants, instead of being wannabes?".
The reality of the religious is that they aren't all the same. Even a Liberal Evangelical would be a holy roller to most Catholics, albeit a tolerable one (the same is true of the Orthodox schism). Catholics and Orthodox kind of like Episcopols, but loathe Baptists (not virulently, but in a more cultural sense).
Moreover, assumptuions based on Evangelicals would inadvertantly be insulting to Catholics and Orthodox. One example I've seen on these boards from some Liberal Evangelicals...it ain't "Christians and Catholics". Even my agnostic self is still enough a Catholic to get annoyed with that. We view ourselves as being the original Christians, and you folks as being, well...a quaint schism. Perfectly valid and all, but still a spinoff. To hear Prots call themselves Christians as some exclusive and seperate concept is, well, a piss off.
I won't even mention how freaked Jews are around overt and aggressive versions of either Catholics or Protestants, given our fabulous history with them.
In addition, Catholics are used to low level hypocricy and ignoring dogma. How many do you know who have sex outside of marriage with birth control. Yet they identify Catholic rabidly. The Pope? Hey a terrific and holy man...but come on...how well can a celebate octagenarian get real life. On the trivial stuff, sometimes it's better to just humor Rome.
My point is that while everyone is chasing the Evangelical or "faith" vote, they miss the concept that these folks don't agree with each other. Go ahead, drop in scripture to speeches...and watch Catholics and Orthodox cringe away. Screw up and call everyone Christians, and Evangelicals will take offense at being lumped in with Catholics. Don't do it, and watch the Catholics get pissed that you gave the term to the "holy rollers".
It isn't as simple as you would like to think. Sorry.