This song in Latin is by Marty Haugen and based on the antiphon from the Good Friday liturgy:
We adore you, O Christ, and we bless you, because by your holy cross you have redeemed the world.
The text is at Hymnary. Haugen’s setting is very like a Taize chant with a repeated refrain and verses sung over them. The refrain is meant for a 3 part canon, which will be 4 parts while the cantor is doing the verses.
I can only find the handbells arrangement at GIA.