During a concert last week, the voices of the Cathedral Children’s Choir rang out with the joy of heaven, while singing the end of “Stabat Mater,” a classic piece of sacred music. Young singers from the choir belted out “Amen” — a prayer for salvation that concludes the piece — which echoed through the Cathedral of St. John the Baptist in Paterson at the end of the performance. Most of the 50 singers practiced while attending the choir’s very first summer camp held during the day from July 10–14 in St. John’s.