Ringed with red poinsettias, Kenneth Slowik and the Smithsonian Chamber Chorus and Players served up a full helping of Bach at the National Presbyterian Church Saturday night. Always an ambitious undertaking, J.S. Bach's "Christmas Oratorio," really a series of six shorter cantatas written for the liturgical feast days of the Christmas season, does not always translate well as a performance work. Intensely personal and small in scale, it lacks the flourishes and drama of the other Christmas oratorio -- "Messiah," which was, after all, written by a composer familiar with popular operatic styles. Bach, a church composer, wrote differently; the arias in his oratorio are subordinate to the religious text, and the chorus work consists of very literal and unadorned chorales, so the overall effect is somber and somewhat tedious. Nonetheless, the dozen or so singers of the Chamber Chorus were well suited to the style of the piece and tenor Patrick Romano gave an excellent and well-articulated performance in the crucial role of the Evangelist. His singing was a bit restrained at first but became more expressive and expansive as the oratorio progressed. The substitution of the countertenor for a boy alto was not altogether successful, but countertenor Steven Rickards showed good depth of tone in a most enjoyable "Schlafe, mein Liebster." Bass Peter Becker delivered a full-bodied "Grober Herr, o starker Koenig," though the orchestra accompaniment pulled apart at the seams a bit.

The well-known aria "Nur ein Wink von seinen Haenden" received a tuneful but choppy handling from soprano Rosa Lamoreaux. The other oft-sung and intimate aria, "Nun moegt ihr stolzen Feinde schrecken," fared better under tenor Robert Craig, who sang lyrically and with energy.

The Chamber Players played well throughout; the oboes especially did themselves proud. The period instruments, though, posed some problems: a few intonation difficulties in the cello and considerable faltering among the brass, particularly the trumpets. A valveless horn is a treacherous animal indeed, and the use of a more reliable modern instrument would be preferable to splattered entrances that marred an otherwise lovely performance. Slowik conducted with gentle refinement, and the capacity crowd rewarded the ensemble's effort with thunderous applause.