While the boy, who cannot be named, was hanging on the crucifix the group drew crosses and phallic symbols on him with permanent marker, which took days to scrubs off and left his skin damaged.
Andrew Addison, 30, Joseph Rose, 21, Christopher Jackson, 21 and Alex Puchir, 37, have all been charged with putting a person in fear of violence by harassment and religiously aggravated assault.
The four men are from a shopfitting company in Selby, North Yorkshire, where the boy was an apprentice.
They deny all the charges against them.
Prosecuting, Austin Newman told York Crown Court: "He was subjected to acts of bullying, which the crown say went beyond anything that could reasonably be described as banter or hijinx.
"The crosses in particular were an indication of the hostility towards [the boy] based on his religious observance."
The trial continues.
