Cantata no. 121: Christum, wir sollen loben schon, BWV.121

Christum wir sollen loben schon (Christ we shall praise splendidly), BWV 121, is a church cantata by Johann Sebastian Bach. He composed this Christmas cantata in Leipzig in 1724 for the second day of Christmas and first performed it on 26 December 1724. It is based on a hymn by Martin Luther, "Christum wir sollen loben schon", a 1524 translation of the Latin "A solis ortus cardine" hymn from the 5th century.

The cantata is part of Bach's chorale cantata cycle, the second cycle during his tenure as Thomaskantor that began in 1723. In the format of this cycle, the text retains the first and last stanza of the chorale unchanged, while the inner six stanzas were paraphrased by an unknown librettist for alternating arias and recitatives. The librettist created a sermon about the miracle of the birth of Jesus and the believer's reaction to it. The work's outer movements are choral and use the hymn tune, while the inner four movements are composed for soloists, unconnected to the hymn tune. The cantata is scored for four vocal soloists, a four-part choir, and a Baroque instrumental ensemble of cornett and trombones to reinforce the voices, oboe d'amore, strings, and basso continuo.