The man, who is now 19, said he believed his colleagues were "taking the mickey" out of his religion and was left feeling distraught by the sustained campaign of bullying.
Andrew Addison, Joseph Rose, Christopher Jackson and Alex Puchir are on trial at York Crown Court accused of religiously aggravated assault against the teenager.
They deny the charges which are said to have taken place when he was an apprentice at the Direct Interior Solutions shop fitting company in Selby, North Yorkshire.
The jury has been told that, on separate occasions between July 2014 and April 2015, the victim also had religious and phallic symbols drawn on his body with permanent marker; was tied to a chair; had deodorant sprayed towards him and ignited; and was given a "wedgie" by his boss.
Giving evidence by video link, the teenager, who was aged 17 and 18 and a student at Selby College at the time of the alleged incidents, said: "(I felt) just ashamed and distraught. I couldn't believe it. It hadn't happened to anyone else."
The man told the court that he was working on a bank refit in Hull, East Yorkshire, in January 2015, when company manager Addison and Jackson grabbed his arms and legs.
He said Puchir was told to make a cross, which he fashioned from two pieces of timber.
"I was then lifted up and put on to the cross and secured on to it," the teenager said.
"I was then put up on to the wall."
The victim told the jury he was suspended about three feet above the floor and said a number of people working on the site had filmed the incident.
He said: "At the time, I didn't really know what to feel. I just felt, like, ashamed that everyone else saw what was happening to me and it wasn't happening to anyone else. I just felt really embarrassed.
"Afterwards, I started thinking maybe they were just trying to take the mickey out of my religion. I didn't really understand why there was a cross made."
The victim told the court he was a churchgoer and said he told colleagues he could not answer his phone on one occasion because he was in a church service.
The teenager described an earlier incident when the company was working on a site in Essex and Rose used a marker pen to cover him "from head to toe" in crosses, penises and squiggles while he was asleep in a hotel room.
He said the incident was "humiliating" and that he felt "stupid" having to go to work covered in pen. He was left with sore, red skin after scrubbing the marks off, he told the jury.
The court has heard that Rose, on another occasion, sprayed deodorant towards the teenager's head and lit it while Addison recorded the incident on his mobile phone.
Addison is also accused of tying the teenager to a chair with duct tape and cable ties and leaving him locked, blindfolded in a room by himself and giving him a "wedgie" by pulling his underpants up so forcibly he was lifted off his feet and suffered cuts and bruises to his buttocks.
The victim told the court that he did not make a complaint at the time of the incidents because he did not want to get sacked, he did not want anyone to know what was happening to him and he was scared of his colleagues.
Addison, 30, of Selby, and Rose, 21, of Bubwith, East Yorkshire, both deny putting a person in fear of violence by harassment and religiously aggravated assault by beating.
Addison also denies a charge of assault by beating. Jackson, 22, of Barlby, North Yorkshire, and Puchir, 37, of Edinburgh, both deny religiously aggravated assault by beating.
The trial continues.