The Baroque Artists of Champaign-Urbana (BACH) concert on Sunday at First United Methodist Church in Champaign had an intriguing central idea. Under the leadership of Sarah Riskind, this ensemble performed the treatments of Psalm 42, “As the deer longs for water …,” by four composers, from the Renaissance to the recent past, Giovanni Pierluigi da Palestrina, Marianna Martines, Herbert Howells and Judith Weir. The latter two composers used the version in the 1662 Anglian Book of Common Prayer.