Victoria Wasteney, a senior occupational therapist, had worked for East London NHS Foundation Trust for eight years before she ran into trouble after being accused of "harassing and bullying" her co-worker by giving her a book about a Muslim woman's encounter with Christianity.
Earlier this year, the employment tribunal ruled that her employers, East London NHS Foundation Trust, were right to discipline Miss Wasteney for praying (with consent) for her colleague, handing her a Christian book and inviting her to church events.
Her lawyers are now seeking the opportunity to fight the case, citing fundamental rights of freedom of expression and of religion.
Speaking at the end of her tribunal in April, she said: "I conducted all my conversations with my colleague in a sensitive and appropriate way.
"I knew she was from a different faith background and I was respectful of that. I didn't force my beliefs on anyone at any point. Surely there should be room for mutual conversations about faith, where appropriate, in the workplace?
"A complaint was made against me by someone who left the job the following month and who did not attend the NHS trust's disciplinary hearing or the Employment Tribunal. Evidence from text messages shows that we had a friendly relationship. I believe that the complaint has been handled in the way that it has because I am a Christian.
"I am extremely disappointed with the Tribunal's decision to side with my employer. There is already an unnatural caginess around faith and belief which is an obstruction to building meaningful relationships in the workplace.
"This decision will only perpetuate that, to the detriment of working relationships in the NHS."
Miss Wasteney is supported by the Christian Legal Centre. Chief executive, Andrea Williams claims she's been treated unfairly. She said: "Victoria has been punished and left out in the cold for being honest and open about her faith and highlights an unhealthy trend.
"Do we want to be left with working environments where people are forced to hide their identity and the things that matter most to them? Such environments are detrimental to meaningful working relationships and ultimately to productivity."