Today a cantor is the person in a church that cares about the musical conduct. He or she is responsible for the singing and for the organ play, he or she heads the choir or choirs and the music ensembles or orchestra. Plus he or she is responsible for the children's choir and the trombone choir. And actually this is what a cantor already was doing in the time of Johann Sebastian Bach. And it's pretty sure, that this is, what Johann Sebastian Bach's job as a cantor was too. Plus, as a Thomas Cantor, more tasks came with his employment in Leipzig.
99 Music Calendars, Composers Calendars and Bach Calendars