Bach's birthday and Adams' enigma.

Two large-scale sacred works, composed 250 years apart, dominate the classical music stage this weekend. The folks at Miller Theatre present the triumphant finale of their year long Bach in Context series, the B Minor Mass, while Lincoln Center, in concordance with BAM, kicks off their retrospective An American Master: The Music of John Adams with the long-awaited New York premiere of his extraordinary recent oratorio, El Niño. The juxtaposition of these two masterworks represents both the continuity and divergence that define the Western classical music tradition.

Bach wrote his Mass in B Minor near the end of his lifetime and, in many ways, it is a summation of his life’s work. The Mass was put together piecemeal over 25 years, the initial inspiration traced back by scholars to a performance of the Sanctus on Christmas day, 1724. Bach finished the work shortly before his death in 1750, and he never heard the complete Mass performed.

On the occasion of the composer’s 318th birthday (March 21), Miller Theatre Executive Director George Steel takes the podium at St. Paul’s Chapel and conducts the Vox Vocal Ensemble and the Gotham City Orchestra and a quintet of soloists in two full performances. In a time when religion is increasingly corrupted by fanaticism and artificiality, Bach’s exhaustingly sincere evangelism, carefully embedded in the perfection of his structural esthetic, is the most persuasive kind of evidence for the existence of universal divinity.

And just as Bach has you convinced that the Mass makes perfect sense, John Adams, firmly rooted in 21st-century America, throws orthodoxy back into question with his interpretation of the Nativity story. El Niño, a multimedia oratorio, moves away from the worn liturgical Latin of Bach and looks for alternate interpretations of the Christmas story. With the help of longtime collaborator Peter Sellars (who directed three of Adams’ previous theatrical works, including Nixon in China), Adams gleaned his texts from more unusual sources. The heart of the work is six poems by two of Mexico’s most renowned female poets, Sor Juana Inéz de la Cruz and Rosario Castellanos.

Focusing on the emotional and physical profundity that surrounds a woman giving birth, Adams’s work gives voice to the voiceless: the women whose points of view are traditionally left out of the Gospel. By making use of both the light vocal quality of soprano Dawn Upshaw and the darker tones of mezzo Lorraine Hunt Lieberson, Adams removes the emphasis from one woman—Mary—and universalizes the theme to address the experience of all women who become mothers. In addition to the poetry, Adams’ trilingual text (Spanish, English, Latin) makes use of several excerpts from the Gnostic Infancy Gospels, a set of alternative accounts offering a less severe view of Jesus’ life.

Musically, El Niño folds the urgency of his earlier minimalist works like Shaker Loops into the more complex harmonic language that has informed much of his more recent work, including the orchestral Naive and Sentimental Music, which will be performed Monday, March 24 by the L.A. Philharmonic at Avery Fisher Hall. Adams spins the poetry and text with shimmering mysticism, transforming a subject that threatens to be quite mundane into a personally exultant reconciliation between tradition and progress.

Adams’ enigmatic score is enhanced by an all-star cast of performers including Upshaw, Hunt Lieberson, baritone Willard White, a trio of countertenors, the Los Angeles Master Chorale, Paul Hillier’s Theatre of Voices, the Brooklyn Children’s Choir and the L.A. Philharmonic led by Esa-Pekka Salonen integrated into a specialized sound environment designed by Mark Grey. Both performances will be preceded by a discussion with Adams and Sellars.

Bach Mass in B Minor, Fri., March 21 & Sat., March 22, at St. Paul Chapel at Columbia University. 2960 Bay (116th St.), 212-854-7799, 7:30 p.m. El Nio, Thurs., March 20 & Sat., March 22, 7:30 p.m., at BAM Howard Gilman Opera House. 30 Lafayette Ave. (Ashland Pl.), 718-636-4100.