BANGOR, Maine — Winifred Mary Murray-Higgins has been singing at St. John’s Catholic Church on York Street since she was a child, but she has never performed a piece like the one she will be part of this weekend in Blue Hill and Bangor.

Murray-Higgins will sing “Membra Jesu Nostri” with the St. John Chamber Choir. A trio of musicians playing string instruments from the Baroque period will accompany the choir. Choir director Kevin Birch will play the continuo, a portable pipe organ.

As a nurse, Murray-Higgins — who lives and works in Bangor — said at a rehearsal Saturday night that she tries to find the right intervention at the right time that is right for a particular patient.

“I think this piece is just exactly right for this time,” she said, referring to the fact it will be performed two weeks before Easter.

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The Chamber Choir, founded in 1995, specializes in a cappella sacred music ranging from early chant to modern works, according to the program notes for the concert. It was founded in response to the Second Vatican Council’s challenge to find practical means to preserve and use the church’s rich heritage of Latin chants and motets, to explore the repertory of music used in other communions and to find new uses for the best of the old music.

“Membra Jesu Nostri” fits into the second category. Composer Dieterich Buxtehude was a Danish-German Protestant who composed the piece in 1680. At the time, Buxtehude was the organist at Marienkirche, or St. Mary’s Church, in Lübeck, Germany.

Sacred music from the Baroque era is performed rarely, according to Birch, who also is the music director at St. John’s.

Each of the seven cantatas that make up the piece begins with an introductory sonata for instruments performed on violins by Heidi Powell and Richard Hsu, both of Ellsworth, and on the viol da gamba, a seven-stringed bowed lute, played by Lisa Nielson of Albany, N.Y.

The composer begins and ends each cantata with a Bible verse. Buxtehude used a medieval hymn cycle, “Salve mundi salutare,” attributed to the Belgian Cistercian Abbot Arnuff of Louivain, to bind together his cantatas.

The literal translation of “Membra Jesu Nostri” is “Body Parts of Our Jesus.” That might be difficult for modern audiences to grasp, so Birch and program note co-author Frank Wihbey suggest that the audience members think of it as “Christ’s Every Sacred Wound” or draw a parallel with the seven last words of Christ to set the meditative tone of the piece.

Beginning with the Savior’s feet, each of the seven cantatas focuses on a body part. The composer takes the listener, standing beneath the crucified Christ, visually up his body to his knees, hands, side, breast, heart and, finally, the face of Jesus.

“Today, it is hard to fully convey the feeling surrounding the poetry of the Middle Ages,” the program says, “especially on religious topics. I believe listeners then, and even in the Baroque period, would have heard these verses as imitating the spontaneous utterances of a saint in an ecstasy of devotion.”

The devotion of many of the members of the Chamber Choir is to the musical rather than the religious fervor of the choral music Birch selects. The group is made up of Catholics, Episcopalians, Congregationalists, secular humanists and doubters. What binds them together is a love of music rather than a devotion to a particular deity.

“This is much more difficult music than what we sing in our church choirs,” Mark Lausier of Bangor, a congregant at St. John’s, said after Saturday’s rehearsal. “It puts you to the test musically.”

“Membra Jesu Nostri” will be performed at 7 p.m. Saturday at Blue Hill Congregational Church, 22 Tenney Hill, Blue Hill, and at 8 p.m. Sunday at St. John Catholic Church, 207 York St., Bangor. The suggested donation is $10.