A senior Roman Catholic bishop has joined the row on allowing gay couples to adopt in Scotland.

The Rt Rev Joseph Devine, Bishop of Motherwell said he would not support “politically correct zealots” and would not “stand by and watch the destruction of Christian values and truth”.

In a letter to First Minister of Scotland, Jack McConnell, he stressed that traditional heterosexual family units were the best prospect for the emotional and psychological well-being of a child.

He suggested scrapping the legislation or testing the issue at a referendum, stating the proposed law was “yet another violation of family life”.

Bishop Divine said: “I am only too well aware, of course, that the conventional family unit is in decline and society is paying the price. But where the traditional family unit does exist, it should for the sake of the children be deemed a far more appropriate refuge for them than exposure to a homosexual or lesbian way of life.”

“No doubt for refusing to pander to the idea that homosexual and lesbian relationships are equal to heterosexual partnerships, particularly those blessed in the sight of God, I shall be termed a bigot by the politically correct hardcore in the Scottish Parliament.”

Currently individual homosexuals can adopt, but their partners have no legal rights. The new law will grant both of them equal parental rights and give same- sex couples the opportunity to adopt.

The Scottish Executive insists the shake-up in adoption laws is needed to widen the number of people eligible to adopt the growing numbers of children in temporary foster care. Last year there were 3,468 children in foster care – the highest total for 20 years. Yet since the 1980s the adoption rate in Scotland has fallen from 1,000 a year to under 400.

Barbara Hudson, director of the British Association for Adoption and Fostering (Scotland), said: “We understand the Catholic church’s position but regret that at a time when there is such a need for new parents, that not all agencies are united in a common message. Peoples’ sexual orientation should not be a factor.”

Senior Bishops are seeking a “conscience clause” giving the church and other faith-based groups the right to reject applicants to their adoption agencies on the basis of gender. They fear Catholic-run adoption societies will be challenged under new laws expected to come into force next year

Calum Irving, director of gay rights group, Stonewall Scotland, told the Herald: “I don’t think it is being politically incorrect to try to find stable, secure homes for vulnerable children. Thankfully we don’t run Scotland based on one man’s interpretation of scripture.”