The Court of Appeal is hearing a legal challenge against the removal of a Christian as a magistrate and NHS director.
Richard Page lost his position as a magistrate in the Family Court after 15 years in the judiciary. He was also sacked as a non-executive director of Kent and Medway NHS Trust.
The actions against him came after he said children do best when raised by a mother and father.
He is being represented at the two-day hearing by the Christian Legal Centre (CLC), which says his sacking was discriminatory and an infringement of his freedom of speech.
Andrea Williams, chief executive of the CLC, said Christians are increasingly unable to express their beliefs in public.
"Richard Page's Christian understanding of the family is being treated as so offensive that those who express it are excluded from public life," she said.
"Christians have tremendous capacity to serve society, but they are not only being told to leave their faith at the door – they are being told they cannot publicly express their faith anywhere.
"As a magistrate, Richard Page only wanted to do what was best for the child – the 'gold standard' for cases involving the welfare of a child. For expressing his well-founded belief that a child will do better with a mother and a father he has been unfairly dismissed and ruled out of public life.
"If Richard can also be thrown out of his NHS post, despite all his experience, for sharing his beliefs, it raises serious questions over how Christians can fully participate in society. His NHS role had nothing to do with his views about the family."
Mr Page said he had mounted the legal challenge because he did not want other Christians to lose their jobs over their beliefs.
"I do not want Christian beliefs to be barred from important positions in public life," he said.
"When you sit in a Family Court, you have a huge responsibility to ensure the overall well-being of the children who are being recommended to be placed into new families.
"You weigh the reports and references before you and the evidence you hear. It is vital in such a scenario that a range of viewpoints are heard. That is why there are three magistrates who preside over a case, and not one dictating the decision.
"To punish and to seek to silence me for expressing a dissenting view is deeply worrying for our society. It is vital for Christians to take a stand for their freedoms, for the truth, and for the futures of our children."