Berlin's acclaimed RIAS-Kammerchor brings us works by a pair of composers, Frank Martin (1890-1974) and Olivier Messiaen (1908-1992), who have few musical features in common, but their faith makes them two of the most important Christian composers of the 20th century. Martin's Mass for unaccompanied double choir is the profound profession of faith of a fervent Christian of our time. The "Cinq Rechants," Messiaen's last a cappella work, was thought of by him as "one of (his) best works." Included here are the 5 parts of Martin's "Mess pour double choeur a cappella" and the 5 movements of his "Song of Ariel;" and the 5 "Cinq Rechants" and "O sacrum convivium" by Messaien. This is deeply spiritual music, alternately lovely, surprising, difficult and eclectic, wonderfully performed by RIAS-Kammerchor.