When the Washington Bach Consort performed its namesake’s “Christmas Oratorio” on Sunday, all you needed to hear was a single aria to understand why the entire show, at National Presbyterian Church, worked as splendidly as it did. The aria, “Flösst, mein Heiland,” is a bit of aural magic in which Bach sets the soprano soloist’s wonder-filled inquiry to God on the mysteries of the afterlife against echoes of her own words by another soprano offstage and an oboe onstage.

Consort Artistic Director Dana Marsh leaned into the aria’s lilting dance rhythms, conducting his orchestra for maximum buoyancy and grace. Floating above their music was a voice with the kind of luminosity one longs for in Bach, that of the marvelous young soprano Elijah McCormack. The spatial placement of Geoffrey Burgess’s oboe and an unnamed soprano chorister for the echo effects caught the glow of the church’s acoustics to perfection, and both artists did lovely work.

That aria was a joy, but so indeed was the entire performance. A chorus of only 16 singers made a bright, forthright sound, its phrasing as word-responsive as its blend was polished and supple. The period instruments in the ensemble were a tight and responsive group and — some fluffs in the punishing high trumpet parts aside — shone in their frequent solo work.

Among the vocal soloists, McCormack did eloquent work throughout, as did bass Steven Combs, with his warm timbre and tender phrasing. Kristen Dubenion-Smith possesses a lyric-mezzo of uncommon beauty, her flickering vibrato and the amber cast of her tone making something special out of the alto arias. If veteran tenor Rufus Müller’s sometimes dry, sometimes crooned top notes now require careful management, few singers can make the role of the Evangelist sound as conversational and lived-in.

But perhaps most of the credit should go to Marsh, who has been able to build on the heady legacy of the consort’s late founder, J. Reilly Lewis. He has honed a company that could go head-to-head with period-performance ensembles anywhere.