Nineteenth-century French composer Hector Berlioz was raised a Catholic but, by most accounts, became an agnostic or atheist later in life. “l’Enfance du Christ,” a work for chorus and chamber orchestra, was thus composed more in homage to religious music than a deep-seated desire to recount the narrative surrounding the birth of Christ.

Unlike the bold, clashing, romantic compositions by which Berlioz is generally defined, “l’Enfance du Christ” unfolds with gentler turbulence and purposeful delicacy. Perhaps that placidity, coupled with its religious theme, is why it was among the best received of his compositions during his lifetime. Berlioz himself was annoyed by, and firmly rebutted, suggestions that he had changed his style for this piece.

Yet its creative process certainly followed a checkered path. In 1850, more than five years before its formal premiere, Berlioz introduced a vocal piece for organ, where shepherds bid adieu to the baby Jesus and his family as they head off to Egypt. But at the time he claimed this “Shepherd’s Farewell” had been written by a 17th Century composer. Heartened by the public response, he dropped the hoax and added an overture and a segment for tenor, creating what eventually became the second movement of “l’Enfance du Christ,” titled “The Flight to Egypt.”

Encouraged by friends to keep expanding the work, Berlioz then added a movement, complete with libretto that he described as “a page out of a missal,” detailing the family’s arrival in Sais, where they are greeted warmly and housed by the Ishmaelites. Only at the end of the process did Berlioz get around to composing the opening to “l’Enfance du Christ,” completing what he called his “sacred trilogy” with “Herod’s Dream,” in which the king, afraid of a dream backed by a soothsaying prophecy that he will be deposed by a child, orders the death of all male children in his realm.

“l’Enfance du Christ” is not among Berlioz’s best-known compositions, nor is it performed very often. But outgoing SPCO artistic partner Douglas Boyd so enjoyed his collaboration with the Dale Warland’s SPCO Chorale last year that he wanted to reprise the experience as part of his final three weeks with the organization. “l’Enfance du Christ” is the vehicle chosen by the conductor to make it happen.

Here is a dramatic television adaption of a portion of “Herod’s Dream.” Here is “Shepherd’s Farewell” portion of the second movement. Here is Douglas Boyd conducting the SPCO and the Chamber Orchestra of Europe through a Vaughan Williams fantasia last year.

SPCO performs Berlioz’s “l’Enfance du Christ” at the Ordway Center, today, Friday and Saturday at 8 p.m.; tickets $11-$50 today and $11-$59 Friday and Saturday.