A Christian nursery worker who was sacked after airing her views on homosexuality and marriage has won a discrimination claim against her former employer, her legal representatives have said.

Sarah Mbuyi, 31, was dismissed by Newpark Childcare in Shepherd’s Bush, west London, for gross misconduct after telling a lesbian colleague her gay lifestyle was a sin. She claimed the sacking breached European law on religious freedom.

The Belgian national, from Tottenham, north London, who had been working for a year with children aged under one, denied harassment and maintained that her colleague approached her asking about religion and same-sex marriage and was angry she had been barred from marrying her partner in a church.

The Christian Legal Centre (CLC), which supported Mbuyi, said an employment tribunal at Watford had found she was directly discriminated against because of her belief that homosexual practice is contrary to the Bible.

The tribunal recognised that while the employer was “not anti-Christian” Mbuyi had not been treated fairly and that the decision to sack her may have been made on “stereotypical assumptions about her and her beliefs”.

Her belief was described by the tribunal as one that is “worthy of respect in a democratic society, is not incompatible with human dignity and is not in conflict with the fundamental rights of others”. It added that the employer’s policy that there was a “prohibition on employees expressing adverse views on homosexuality and/or describing homosexuality as a sin” would have a “disparate impact on Christians holding similar views to Miss Mbuyi on the biblical teachings on practising homosexuality. That is not merely because a significantly higher proportion of Christians would hold such views but also because many evangelical Christians feel their faith compels them to share it.”

The tribunal found that Mbuyi’s colleague had clearly indicated that she had first expressly brought up her sexuality in conversation with Mbuyi and there was little or no evidence to suggest Mbuyi targeted her colleague in an attempt to force her faith on her.

It said the internal investigation by the employer was hampered by the “stereotypical assumption about evangelical Christians” and that the employer either “pre-judged the outcome accepting unchallenged evidence that supported the stereotypical assumption and/or interpreted Miss Mbuyi’s evidence in an almost impossible way”.

Andrea Minichiello Williams, barrister and chief executive of the CLC, said: “This is a brave judgment and comes as a great relief to Miss Mbuyi and to all of us at the Christian Legal Centre.

“This judgment is a ‘common sense’ judgment which shows understanding of the Christian faith and Miss Mbuyi’s freedom to live and speak it out in the work place.

“We have been in the employment courts for over a decade now and at last we have a sensible decision.”

Mbuyi is now working as a nanny elsewhere. She spoke of her relief at the outcome, saying: “I only ever responded to questions that my colleague asked me and wanted the very best for her. I give glory to God for the decision and say ‘well done’ to the Christian Legal Centre.

“I hope that my previous employer and colleagues are well and will understand from this that my intention was for their best.”

Tiffany Clutterbuck, a director of Newpark Childcare, told the Sunday Times she was disappointed by the ruling, adding: “We have robust policies and rules to ensure our nursery is inclusive and supportive for our children and staff and we took the decision to dismiss Miss Mbuyi with a view to protecting that culture.

“However, the tribunal found Miss Mbuyi’s actions were not harassment of a gay colleague and that she was entitled to express her religious beliefs in the workplace in the context of the conversation which took place. Our priority will always be to provide an environment where every child feels like he or she belongs.”