FUERZA is the Spanish word for "fortress" or "refuge" (see both Psalm 46 and the text). The repeated refrain or antiphon is intended for unison singing, but the melody of the stanzas suggests two-part singing in typically Spanish parallel thirds. Try using a duet or two-part choir on the stanzas and have everyone sing the refrain. Since the stanzas are rather high and the refrain rather low, have the congregation sing the refrain and a duet or two-part choir sing the stanzas. Also, since the refrain is repeated each time, try to sing the refrain in English the first time through and repeat it in Spanish.
--Psalter Hymnal Handbook, 1988