The Bible's teaching on marriage "cannot be set aside", bishops have warned ahead of a debate in the Church of England on allowing blessings for same-sex couples.

Two dozen bishops have published a paper explaining why they believe that any change to the doctrine of marriage as a lifelong union between a man and a woman will "unravel the Scriptural story of salvation" and "risk undermining our understanding of the nature of the Church".

The paper is the work of two dozen bishops, with contributions from the Bishop of Coventry, Christopher Cocksworth, the Bishop of Sheffield, Pete Wilcox, the Bishop of Lancaster, Jill Duff, and the Bishop of Fulham, Jonathan Baker, who provides alternative episcopal oversight in the Dioceses of London and Southwark.

They argue that the Bible, from Genesis to Revelation, consistently teaches heterosexual marriage.

The bishops write that holy matrimony is a "witness" to the Gospel that "needs to be preserved".

They also argue that procreation is "central" to the character of marriage, and that sexual and biological differences matter.

"Modern anthropologies may suggest that sexual difference and biology are unimportant or irrelevant," the bishops said.

"Yet Christian faith has always insisted that Creation, even though fallen, retains goodness at its essence. In the Genesis account, sexual difference is part of Creation not the Fall, and so we relate to God and each other in these two forms as male and female.

"Marriage therefore, as the union of man and woman bears witness not to the accidental or arbitrary nature of God's creation of male and female, but to its goodness."

Elsewhere, the bishops write that heterosexual marriage "a symbolic statement that is intrinsic to the nature of the Church" and "a sacramental sign of something bigger than itself".

"That signification depends to a significant degree on sexual difference," they write.

"Every marriage is thus a proclamation of the gospel. It bears witness to God our Creator and Redeemer; to God's nature, purposes and love.

"This is a picture of reality that matters for Christians, and the framework within which the Christian doctrine of marriage sits and from which the Church's sexual ethics properly flow."

The paper ends with a call to preserve current doctrine.

"Any change to the doctrine of marriage as a union between a man and a woman would therefore not only unravel the Scriptural story of salvation, but risk undermining our understanding of the nature of the Church as it is derived from Scripture and given to us as a revelatory sign. Marriage is essentially an ecclesial, as well as a human, instrument of unity," the bishops conclude.

The paper has been written in response to plans announced last month to permit services of blessing for same-sex couples.

'The Prayers of Love and Faith' will be debated at the forthcoming meeting of the Church of England's parliamentary body, the General Synod, next week in London.