December is the month for sacred music and the very first evening included a fine performance of the Mass in B Minor of Johann Sebastian Bach presented by the venerable National Chorale at Avery Fisher Hall. Although many assume that this ensemble is based in Washington, it is a New York institution, mounting high quality choral events at Lincoln Center every year since 1967.

Two facts are certain about this mass. First, Bach never presented it in his lifetime. Second, it contains much material previously employed at various services or for assorted commissions. Beyond these points, there is little agreement about the work. The composer may have been working on the piece when he died, but it is just as likely that it had been shelved as an unmarketable pastiche. Bach, a Lutheran, wrote most of his sacred pieces in German, although it was still the tradition to intersperse Latin movements into the text. However, the B Minor is in full Latin regalia and would have had to be for Catholic consumption. Bach, ever the salesman with a huge inventory, had most likely fashioned its skeleton in anticipation of a commission that never materialized.

Music Director Martin Josman has solved the orchestration question deftly by employing a small modern chamber ensemble but reserving the obbligato parts for period instruments — what the Baroque masters might call a “festival” approach. He knows that it can’t be all about the singing unless everything else is working properly, and this handpicked band played splendidly. It was an essential part of the rather rough-and-tumble, spare, and muscular sound of this performance, light-years away from the opulence of the mid-20th century, when conductors like Otto Klemperer redefined the Bach experience as a kind of gargantuan proto-Romanticism. The National Chorale is much closer to what most scholars believe was the rather austere sonic experience of the 1740s.

The chorus itself is engineered for this type of athletic expression. Though relatively small — certainly by today’s standards — the individual sections did a fine job. Sometimes one group or another waxed too poetic in one of the more ecstatic spots, but Mr. Josman was ever vigilant and ready to return them smoothly to the fold.

The soloists were a mixed bag. Bass Jason Hardy, who was impressive last season at City Opera in Handel’s Acis and Galatea, was in finest voice, nimbly presenting the Et in Spritum sanctum section of the Credo accompanied by Diane Lesser, oboe d’amore and Charles McCracken, bassoon. Tenor Nils Brown, however, got off to a discordant start: The tenor is not allowed to sing in this mass for a very long time and Mr. Brown may have simply been no longer warm from his pre-concert exercises. As a result, he took a while to right himself.

Alto Svetlana Serdar has a strong voice and used it effectively in such passages as Qui sedes ad dextram Patris. Her duet with soprano Jee Hyun Lim, the Et in Unum Dominum, however, exposed the fact that she is much smoother in line than her higher-voiced counterpart, who had a somewhat choppy evening, often swallowing her phrases before their natural fruition. Ms. Lim’s opening Laudamus te was rushed and surprisingly weak. But as a totality, this was astute music making.

A curious program note at this concert asserted “people of every, or no faith find unique inspiration and beauty in this powerful work.” That most spiritual of composers, Anton Bruckner, never began a day of composition without first running through a few Bach preludes at the keyboard. Atheists who love Bach might actually have more genuine, albeit sublimated, faith than they are willing to acknowledge.

But people — of faith or otherwise — were lacking this night. It was quite disappointing to see such a small turnout at the huge hall. If you took away the friends and relatives of the performers, you would have been left with just a handful of dedicated listeners.

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Bach’s secular music is also popular at Christmas, and on the second night of the commercial advent calendar, the leaderless chamber orchestra Orpheus offered two of his Brandenburg Concertos as the confection behind the little door. For this concert at Carnegie Hall, it also presented two other works related to these timeless gems, one quite closely and one decidedly from a distant branch of the family tree.

The program began badly with a surprisingly sloppy realization of the Brandenburg No. 1. After just hearing such a tight performance of Bach by the National Chorale Orchestra, it was a bit of a shock to sit through such flabby enunciation, the strings unfocused and each going their own way, the horns sliding around in search of one note on pitch that continuously eluded them. Orpheus rotates its string players, so it was merciful that tonight’s violin soloist was anonymous, as she struggled throughout the piece with poor intonation, equivocal declamation, and uneven technique. Orpheus, as part of its identity, has always had quick turnover, and its present iteration is far from the remarkably disciplined original ensemble.

Things got only marginally better as pianist Jeremy Denk joined for the D minor Keyboard Concerto. The accompaniment was a little clearer, being only strings, but Mr. Denk’s pianism exhibited a little slovenliness. Bach creates tremendous tension in the opening Allegro, but it was severely deflated by Mr. Denk’s loose approach that ran one note into the next. He eschews dynamics, which certainly can be justified from a scholarly point of view but is questionable aesthetically. As a consequence, there was little buildup of friction and, therefore, no orgiastic release.

Orpheus commissioned a work especially for this evening, the first of six “new Brandenburg” concertos. Stephen Hartke, a New Jersey composer now living in Berlin, wished for his “A Brandenburg Autumn” to be “as unlike Bach as possible.” I can state with certainty that he accomplished this goal.

Except for a few rare instances, Bach did not write program music, and Mr. Hartke’s piece consists of three musical pictures. Although the second, Scherzo: Colloquy, was much too broad of a caricature for my taste, I was at least mildly intrigued by the outer movements. Nocturne: Barcarolle is a depiction of a lake near Brandenburg, Germany, complete with bobbing boats, while Sarabande: Palaces reconstructs a walk through Potsdam. These were innocuous landscapes fashioned with a decidedly tonal vocabulary.

It was obvious Mr. Hartke received the lion’s share of the precious rehearsal time needed to mount such an event. It was also clear to observe, if heretical to state, that his guiding hand during those rehearsals had made the difference: When the players were conductorless, they drifted rather far from their aim of precise and profound Bachian presentation.

Unfortunately, the Hartke was introduced with a lecture from one of the cellists, who, in three minutes, deemed the new work “great” no less than four times. Please don’t gild the lily, folks. Rather, present the piece in the best light possible and allow your audience to draw its own conclusions. When I returned from intermission and saw the microphone set up at the side of the stage, my only regret was that my colleague Jay Nordlinger was not in attendance. I know how much he enjoys these in-concert talks.

At least all ended well with a decent rendition of the Brandenburg No.2, with Carl Albach taming the beast that is the E Flat trumpet. It’s difficult to understand how, with no conductor, Orpheus can improve as it should. Perhaps it should hire someone it trusts who can just sit there and listen.