An electrician and former soldier faces the sack for placing a small palm cross on the dashboard of his company van.
Bosses at the housing association where he has worked for 15 years have asked Colin Atkinson to remove the religious symbol because it could offend tenants.
But the 64-year-old has refused to comply with their demands and now the long-serving employee may be forced to attend a disciplinary hearing.
His company, publicly funded Wakefield and District Housing (WDH) - which claims to be a neutral organisation and "among the top 10 employers in the area" - has said allowing a cross would be showing favour to Christianity.
"I'm really shocked and surprised by all of this," Mr Atkinson said. "I have always had that cross in my van. It's a symbol of my personal faith. It's not offensive. It's in a discreet place and I am acting lawfully."
The Wakefield-based not-for-profit organisation launched an investigation after it received a written complaint from a tenant relating to the eight-inch cross made from woven palm leaves.
Mr Atkinson could now lose his job over his alleged failure to comply with company policy which prohibits employees from displaying personal items in the firm's vehicles.
Andrea Minichiello Williams, CEO of the Christian Legal Centre which is supporting his position, hit out at what she termed an "illiberal" and "remarkably intolerant" request.
"Colin Atkinson is a decent and hard-working man, yet after many years of service he has been told that he cannot continue to have a small palm cross in his van," she said. "This smacks of something deeply illiberal and remarkably intolerant. Freedom of expression now needs to be robustly defended. When a man can't display a palm cross in his van in a historically Christian country, it should give people serious pause for thought. Is this the kind of society that the British public want to live in?"
WDH employees who adhere to other faiths are allowed to wear head-dresses and turbans, but the company said all its drivers were subject to the same rules. "We do not allow employees to display any personal representations in our vehicles, although they are free to do so upon their person," a spokesman said. "It would be inappropriate to comment further about this individual case."