An adviser to an adoption panel was dismissed after refusing to recommend children live with same-sex couples, an employment tribunal has heard.
Dr Sheila Matthews, 50, from Kettering in Northamptonshire, lost her job with the county council when she asked to abstain from voting in same-sex cases.
She told her employers Northamptonshire County Council she felt that children "did best" with heterosexual parents.
She is bringing a claim of religious discrimination against the council.
Martin Pratt, the council's former head of services for children, said the authority wrote to Dr Matthews in April last year to terminate her position on the panel after she told him she was unable to set aside her beliefs on the issue of same-sex couples.
He told an employment tribunal sitting in Leicester: "I asked her whether she could consider applicants on their merits ... and she said she could not.
"She did not believe it was in the interests of the child to be adopted by a same-sex couple."
Mr Pratt, who now works for Luton Borough Council, added: "Primarily it was a religious matter, I think. Her inability to act fully in her capacity posed a serious problem."
In a statement released by the Christian Legal Centre, which is supporting Mrs Matthews, she said: "I understand that legislation permits same-sex couples to adopt and they are positively encouraged to apply."
But, she added: "I have professional concerns... of the influences on children growing up in homosexual households and I feel this is not the best possible option for a child.
"I do not consider myself to be homophobic, however I believe that children do best in families with a father and mother."
She added: "I believe it could have been possible for the county council to have allowed me to continue working as medical advisor... but also allow me discreetly to abstain from voting in less than one in 20 cases."
The tribunal was adjourned until Tuesday morning.