A most intriguing holiday musical offering, this Chicago Chamber Choir potpourri features a pair of unusual sacred pieces that are seldom played nowadays. Oratorio de Noel (for chorus, soloists, harp, and organ) by Saint-Saens borders on the camp in its mock solemnity punctured by rousing exhortations from the organ. The third grouping of Gustav Holst's Choral Hymns From the Rig Veda (for female chorus and harp), in contrast, delves into the Indian mysticism of its Sanskrit source in achieving an ethereal sense of timelessness. More in keeping with tradition is Michael Praetorius's Puer Natus in Bethlehem, an impressive whiff of baroque piety. The quartet of soloists--Cecilia Razo, Marney MacAdam, Edward Ozaki, and William Mulcahy--are relative newcomers but should shine under the sturdy and sensitive guidance of George Estevez. Accompanying the choristers are the Chicago Symphony's Edward Druzinsky (harp) and CCC's own Dexter Bailey (organ). Sunday, 3:30 PM, Saint Pauls United Church of Christ, 2335 N. Orchard; 935-3800.