A Christian couple "were doomed" not to be allowed to foster children after it emerged they disapproved of homosexuality, a court has heard.
Eunice and Owen Johns, 65 and 62, cared for about 15 children in the 1990s.
They withdrew an application to Derby City Council to become respite carers after a social worker expressed concerns about their opinions.
The High Court is to decide if it is lawful for foster carers to be turned down due to their religious beliefs.
The council said it could not comment but backed the need for clarification on the policy for approving foster carers.
Mr and Mrs Johns' lawyer, Paul Diamond, told the court issues were raised over the couple's suitability as foster carers in 2008 after they told social workers they could not tell a child a homosexual lifestyle was acceptable.
"I will be submitting that the promotion of values is something the court should be protecting and promoting especially when these religious values are recognised as giving a moral framework to values in our country," said Mr Diamond.
"No one is disputing that the duty of every public authority is to safeguard and promote the welfare of a child."
The Pentecostal Christian couple have denied being homophobic, but are against sex before marriage - and by marriage, they do not recognise civil partnerships between gay couples.
This is at odds with Derby City Council's equality policy, which was drawn up under the terms of the Sexual Orientation Act.
The case has been taken up by the Christian Legal Centre, who said it was the first time a court had been asked to decide how local authorities should deal with foster carers who have religious views on sexual ethics.
It said in a statement: "The council has an obligation to respect the Johns' religious beliefs, but also to comply with equality law, which prohibits discrimination because of sexual orientation.
"The case will decide whether the Johns will be able to foster without compromising their beliefs."
However, the lesbian, gay and bisexual rights charity Stonewall have previously backed concern about the couple's views.
Chief Executive Ben Summerskill said: "Too often in fostering cases nowadays it's forgotten that it is the interests of a child, and not the prejudices of a parent, that matter.
"Many Christian parents of gay children will be shocked at Mr and Mrs Johns's views, which are more redolent of the 19th century than the 21st."
The case is being heard in the High Court, sitting at Nottingham Crown Court.
Derby City Council will make submissions to the judges on Tuesday, after which the case will be adjourned for a written judgment to be given at a later date.