That simplicity is a virtue was never more evident than in the program of American Church Music Paul Callaway and the Cathedral Choral Society presented at the Washington Cathedral yesterday.

Amidst anthems and service settings by Parker, Ives, Sowerby, Rorem, Hoiby and Coriglano - some of them lovely, some dreary - came the premiere of John La Montaine's "The Whittier Service." The set of nine hymns on Whittier texts for choir, organ and guitar are splendid in their simplicity, and clearly destined to long and vigorous lives in churches of all sizes and denominations.

In his program notes, La Montaine acknowledges the influences of the British, Europwean and folk traditions on this music, and indeed, they proclaim themselves throughout. But most clearly heard is the folk. These are settings that the most modest choir might aspire to sing. They are delightfully varied and can only enrich the already rich repertoire.

Only the ending, with its unexpectedly melodramatic hype, was poorly conceived and sounded out of place.

Callaway led the Choral Society in a performance that emphasized sympathy with this music. Their pianissimos were beautifully produced and their sound, well balanced, The same, however, cannot be said for the guitar which was amplified out of all proportion.

The chorus sang with conviction, although diction and pitch could have been better disciplined. Soloists Charlae Oaker, Beverly Benso, Douglas Robinson, and Richard Dirksen performed competently, and Callaway did everyone a service by putting together an interesting program.