altar boy:
(plural: ‘altar boys‘)
a boy who helps a priest during (Christian) Roman Catholic religious services;
a server at the altar; an acolyte,
a group of altar boys at the altar of a church
In the past, girls were not allowed to serve at the altar with the altar boys.
It is surprising to learn that Fidel Castro, the Communist leader of Cuba, was an altar boy when he was young!
There are numerous reports that many Christian priests have behaved improperly with their altar boys.

