An interesting issue recently came up in our parish (a very typical medium-sized parish) concerning the sung Mysterium Fidei, and our experience might have implications for others who might be dealing with this or other similar issues.
Our schola over four years has systematically introduced most of the ordinary parts of the Mass in Latin with simple settings as well as a consistent use of the Communio and sometimes the Introit from the Gregorian Hymnal (Solesmes), in addition to employing solemn hymnody. One small piece we haven't really tackled--for a variety of reasons generally classified as "pastoral"--is the sung "Mystery of Faith" and "Memorial Acclamation," which are still in English.
For the tune, we have used a slight leftover from the old days (1970s) of the ubiquitous "Mass of Creation"--not repeated and not accompanied and chant-like, but still suggesting, for those who know, a slight shadow of an unfortunate period in music history. There have been so many other issues to deal with that we just left this one alone.
It worked well enough, and is not disruptive (as the sung MF and MA can often be!). In any case, the choice of Latin ("Mortem tuam annuntiamus, Domine, et tuam resurrectionem confitemur, donec venias"—text and music written especially for use in the 1970 Missal) seemed unviable for us, and experience suggests that an unsuccessful attempt to introduce Latin can come at a high price in terms of parish support.
Then we were sent a new pastor, a person who is often in a position similar to that of a house shopper who, better than the owner, sees the strengths and flaws of an interior design or paint color. The way our schola had done the Mystery of Faith was on his nerves for reasons he couldn't entirely articulate other than to say it seemed too slow, seem truncated and out of place, and generally just didn't fit. He seem torn between asking us to do the entire Mass of Creation (purgatory!) or finding some other solution.
We knew we had but one chance to find that "other solution." We had to find a setting that would be instantly accessible (participation!) but would integrate with the rest of the Mass. So we hit the books and found what we should have found years ago: the plain Gregorian setting rendered in English. Perhaps this is sung all over the world but somehow this obvious solution evaded us for years. But it is truly wonderful: not as long as the Latin and therefore less imbalanced somehow, with words that are familiar to everyone so there is no struggle over text.
In any case, we went over it and over it in rehearsal to make sure that the schola could sing it with great confidence with the proper inflections and style. Just this last week, it was done for the first time. It was a smashing success: stately, calm, intuitive, nondistruptive, and very beautiful overall. For reasons that are still not entirely clear to me, everyone sang it. The new pastor just loved it, and we were spared the fate of adopting a 70s-80s setting with a popular feel.
Yes, there are other solutions, and probably better ones like leaving out the congregational response altogether, but we all deal with existing constraints. And of course no one came up to us after and said: "Hey ya’ll, that was a great Memorial Acclamation!" It is a small change but it helps us move toward that ideal of an organically integrated liturgy that provides a seamless environment for prayer.
What lessons did we learn?
1. Even the smallest shred of problematic music can be, well, a problem; a schola shouldn't be satisfied until it has replaced it all with truly sacred music (as defined in the General Instruction) with due regard for political and pastoral sensitivities of course.
2. If you are unclear about which direction to go or where to turn to solve a liturgical music problem, return to the basic with the Gregorian itself, even if it has to be rendered in the vernacular. The plain chant is always the best starting place.
3. Don't ever assume that a pastoral mandate for change necessarily spells disaster; it could actually offer an opportunity for change in a positive direction.
(Since this is my first post, let me say that I am a member of the St. Cecilia Schola in Auburn, Alabama, and honored to be its director.)