In an article in the Mothers' Union quarterly journal, Home and Family, published on Monday, a senior union member described the nuclear family as 'seen by many to be too stifling, secretive and imprisoning'.
The Mothers' Union, whose stated purpose is 'to be concerned with all that strengthens and preserves marriage and Christian family life', sparked controversy last year with a debate on prostitution.
In the journal, Christine McMullen, a former union central vice-president, says that the nuclear family is not a blueprint with divine endorsement. She notes that the rules applicable to families in Christ's time would not apply today. She adds that many biblical families had love, hate, incest, prostitution, jealousy, theft and disbelief in them, yet God still loved them. Ms McMullen argues that Christ had no home, and that he called married men to abandon their families to follow him.
She recommends a return to the Old Testament model of large collections of families in a clan or household - 'a model we could do well to revert to now the nuclear family is seen by many to be too stifling, secretive and imprisoning'.
'We can think of a family in terms of . . . a mother, father and two children, or a single parent and some children, or an elderly couple being looked after by a son or daughter. A family can be people joined together by blood ties or joined by promises to each other.'
Regarding single-sex marriages, Ms McMullen said yesterday: 'I myself would look at what the Christian values are within that context - commitment, increasing growth, mutual support. If they were there it would be quite reasonable.'
Margaret Duggan, the editor of Home and Family, defended her decision to publish the article. She said it was intended to encourage debate among the union's 650,000 members in preparation for the Year of the Family which starts in November next year.
She said: 'There are going to be some of our older members who . . . feel this is not quite in line with the Mothers' Union as they knew it, but the Mothers' Union is trying to be realistic.'
Ruth Hook, author of the successful book, Choosing Marriage, and a former diocesan vice president of the union, said: 'This article comes as a jolt to our complacent thinking about the family.'
Mary Whitehouse, the anti-pornography campaigner, said: 'Anything that undermines the family inevitably has an effect on all of us. The author reads a different Bible from what the majority of people read.'