(RNS) The growing trend to what he called "deliberate childlessness" on the part of married couples has come under fire from Anglican Bishop Michael Nazir-Ali of Rochester, England."In an age of excessive self-regard and encouragement on every side to the new religion of the 'me,' it is very important for the church to continue saying that having children and their nurture is a basic good of marriage and not just an optional extra," the bishop wrote in the current issue of his diocesan newspaper.Church teaching, he said, argues that marriage is not a matter of self-indulgence or even a prolongation of "romantic" love but rather "costly self-giving to one another and to any children which are born." Such teaching is "crucial" if the social fabric and future generations are not to be further undermined.Nazir-Ali allowed for exceptions to the general rule: those past the age of child-bearing; those unable to have children; and those who should not have children because of the risk of passing on inherited disorders.But those exceptions should not obscure the normative teaching of the church, he said. "It is always a mistake to confuse 'exceptions' with the rule."Emphasizing that sex without commitment was "irresponsible and exploitative," Nazir-Ali, who is married with two as yet unmarried sons in their 20s, said: "Sex with commitment is properly expressed in the context of a married relationship which is permanent. Children are part of God's will for marriage unless there are very good reasons to the contrary. The planning of a family is however part of our stewardship of creation."