Religioso
Devout, religious.
What it means
Religioso means “devout, pious” and calls for a performance of spiritual collectedness: calm, serious, without outward effect. The German equivalent is andächtig.
What is meant is an attitude expressed in several means at once: an even, calm tempo, balanced dynamics in the medium to soft range, bound lines, chordal clarity. Often a chorale-like tone is meant, even in instrumental music.
Religioso differs from the words for calm — tranquillo, gelassen — through its seriousness and spiritual reference. It differs from sostenuto, which calls for sustained playing, in that it designates a character and not a manner of playing.
In the notation
The word stands in italics above the staff, alone or after a tempo word, and applies until a new marking. It is often found over sections with a chorale-like texture: even note values, four-part chords, little ornamentation.
Musical use
The designation is used in sacred music but also in secular works that strike a sacred tone — for instance when a chorale is quoted or a section is to take on a solemn, serious character. In the orchestral and piano music of the nineteenth century it often stands over such quotations and insertions.
Two well-known examples are the Andante religioso, the slow second movement of Mendelssohn’s Organ Sonata No. 4, Op. 65 (1844/45), and the Adagio religioso of Bartók’s Third Piano Concerto of 1945, in which a string introduction is followed by a chorale on the piano. The dynamics are usually held back, but the tone must carry. Devotion must not tip over into ponderousness: the music should flow calmly.
Performance practice
Keep the tempo even and forgo rubato. Play chords in balance, so that no voice stands out, unless something else is notated. Keep the dynamics calm and avoid large intensifications. And leave room at phrase endings without losing the pulse — chorale-like music breathes at the line endings.