The Head of the Anglican Church rejects the redefinition of marriage.
The law has no right to legalise same-sex marriage, the Archbishop of Canterbury declared yesterday.
Dr Rowan Williams said a new marriage law for gay couples would amount to forcing unwanted change on the rest of the nation.
He also said it would be wrong to legalise assisted dying because of the threat it would pose to the vulnerable and because it would go against the beliefs of most people.
In a key speech on human rights, the head of the Anglican Church put his weight behind other leading clergy who have launched a powerful campaign to prevent David Cameron from going ahead with his plan to allow the full rights of marriage to same-sex couples.