Klaus Mertens and consistency, Klaus Mertens sang in every piece that required a bass soloist, 190 in all." He is also involved in the project Dieterich Buxtehude – Opera Omnia of the same ensemble to record the complete works of Dieterich Buxtehude, begun in 2005. As a singer of lieder, he has interpreted songs of Claudio Monteverdi, Antonio Caldara, Wolfgang Amadeus Mozart and Franz Schubert among others. He has performed the title roles of the romantic oratorios "Elijah" and "St. Paul" by Mendelssohn and, as music of the 20th century, Paul Hindemith's "Requiem" and Igor Stravinsky's "Oedipus rex". In the classical repertory
Elijah John was the spiritual successor to Elijah. In the Nativity of St. John the Baptist in Luke, Gabriel appears to Zechariah, John's father, and told him that John "will turn many of the sons of Israel to the Lord their God," and that he will go forth "in the spirit and power of Elijah" (). In the Gospel of Luke, Herod Antipas hears some of the stories surrounding Jesus Christ. Some tell Herod that Jesus is John the Baptist (whom Herod had executed) come back to life. Others tell him that Jesus is Elijah. Later in the same gospel, Jesus