Although New Yorkers are expected to be agog over the 90th birthday of Leonard Bernstein, 2008 will also see the 100th anniversary of a much more significant composer, Olivier Messiaen. At least two festivals are already planned that will offer Messiaen’s complete works for organ, and the performer of one of these cycles, John Scott, presented a preview of his series at St. Thomas Church last week.

Messiaen, who died in 1992, is the last great composer. A devoutly religious man, he strove in all of his mature works to express his profound wonder at the glory of God. Messiaen, like Bruckner, constructed huge orchestral scores, but made his living as a church organist, primarily at Sainte Trinite in Paris. “La Nativité du Seigneur” is an early piece, one of two colorful, episodic essays on the Christmas miracle.

Unlike “Vingt Regards sur l’Enfant-Jésus,” a gigantic meditation for piano, “La Nativité du Seigneur” is more conventionally descriptive — programmatic, if you will. There are nine sections and the work lasts around one hour. At least for the beginning of the piece, the church was filled to capacity.

One of the great pleasures of the LP era was a complete set of Messiaen himself performing his complete works for organ; Mr. Scott gives him a good run for his money. He did a good job of “staging” the work. The church was darkened significantly, with only candles or their electronic equivalents for illumination. Mr. Scott and his instrument were invisible up in the loft, the nebulous locus of the music helping to create the properly mystical mood. A very brief reading from Scripture preceded each of the movements.

The narrative is occasionally interrupted with meditation, so there are really two types of description in play. The composer even went so far as to identify what colors he envisions for each section of music, and Mr. Scott emphasized the kaleidoscopic color scheme of the work as a whole. Unlike Curlionis or Scriabin, Messiaen does not actually project an accompanying light show, but he does labor intensely to create a synaesthetic effect. When he describes the holy glow surrounding the manger, he suggests “violet blue, flecked with red, gold, and silver.” During these storytelling passages, the music remains extremely vivid, with the individual congregants allowed to visualize the scene each in his own manner.

Certain movements are interludes of meditation. These are the more powerful and establish the spiritual nature of the work as a whole. The third movement is intensely reverberant and transporting. The fourth, titled The Word, is dark and foreboding. Messiaen, a student of Dukas and a teacher of Boulez, was an ardent Wagnerian. The early sections of this essay are evocative of Act II of Siegfried, which deals with the nature of fear. Out of this fortissimo maelstrom emerges a meandering and ruminative solo for cornet that, in Mr. Scott’s hands, was particularly affecting.

The entire performance was challenging, inspiring, uplifting. When the bells of the hour chimed outside during the Children of God movement, the moment was perfect. The frenzied, avian cries of the birds mixing with the glorious sounds of the angels was thrilling, the entire movement, titled Jesus Accepts the Suffering, a reminder that the cross appears at the nativity, almost too intense to bear. A superb combination of performing skill, compositional genius and appropriate venue.

The performance followed a sophisticated traversal by the St. Thomas boy choir of “A Ceremony of Carols” by Benjamin Britten, that charming work of innocence that the composer penned on a long sea voyage home from Halifax.

Musically, if not theologically, one can never have too many Messiahs. So while the New York Philharmonic was offering their annual Handel event up the street, I ventured to Carnegie Hall to attend what was billed as a Messiah with a difference.

Musica Sacra delivered a performance that was notable for its freshness and alacrity. The organization originated at the Central Presbyterian Church, where Charles Ives used to play the organ. With music director Richard Westenburg under the weather, associate conductor Kent Tritle, who was already scheduled to lead Messiahs with his Oratorio Society of New York, was pressed into service.

He constructed a brisk reading of the old chestnut, employing smaller forces than a listener might expect at so vast a hall as Carnegie. With only 34 singers — decked out in black with red neckwear for the women and matching boutonnieres for the men — and a mere 27 instrumentalists, Mr. Tritle’s forces were built for speed. When Mozart conducted Messiah, he had even fewer at his disposal, but there have been realizations at places like the Royal Albert Hall, whose participants have numbered over 500.

The other big difference in this rendition was the inclusion of a countertenor. That, at least, was the plan, until the man selected was unable to perform. Ian Howell, who often sings with the a cappella group Chanticleer, filled in.

The aggregate result was a very nimble reading, clean and crisp with all of the vocal lines clearly distinguishable. The orchestra, with no brass section other than two trumpets, was pleasantly propulsive, and Mr. Tritle never allowed the energy to flag. The chorus was bright and often radiant. Still, there was a palpable lack of heft throughout, a little sense of puniness, reminiscent of the symphony that Leopold Mozart wrote for toy instruments. Charming to be sure, but a bit wan.

The soloists were all good in varying degrees. Tenor Rufus Müller was the standout, showcasing a powerful voice and an exceptional ability to hold on individual notes. Of the quartet, he had the most conversance with ornamentation. His “Ev’ry valley” was a delight. There was reason to rejoice greatly in soprano Leslie Fagan, who was similarly confident. She seemed a bit nervous at the outset and this caused her to sound a little tight, but she loosened up quickly and delivered interesting fioriture on demand. Her duet, “He shall feed His flock like a shepherd,” with Mr. Howell was quite satisfying.

Mr. Howell has a uniquely high voice and, by and large, handled it competently. Where he ran into trouble was in pitch control. Several key moments were diminished by his flatness in passing notes. Baritone Benjamin Clements earns a passing grade, but seemed to be less polished than the rest, reminding of a steady church singer thrust into a soloist position without being quite up to par.