In December, the church announced vicars would now be able to hold a special service so transgender people could celebrate their new identities.

But there has been a steadily growing backlash to the proposals, culminating in the open letter which attacks them as "deeply concerning" and "lacking in serious theological analysis".

The signatories caution rapidly-developing theories about gender could cause "more harm than good" to children experiencing gender dysphoria and call on the Church of England's House of Bishops, which approved the reforms last year, to "revise, postpone or withdraw" them until concerns have been addressed.

The letter states that while gender dysphoria was an "emotionally painful experience that requires understanding, support and compassion", the House of Bishops appears to have ignored the potential for damage caused by "novel and largely untested theories about sex and gender".

It also argues the guidance implicitly undermines the church's understanding of marriage by endorsing the idea there is no difference between male and female.

Among the senior Anglicans who have added their names to the letter are two archdeacons, two former bishops, and a member of the Archbishops' Council, one of the C of E's central governing bodies.

Among the other groups to have criticised the new liturgy is the Church of England Evangelical Council, which said in a statement the guidance was "highly divisive and theologically and pastorally questionable".

Even the Bishop of Blackburn, a leading evangelical who had piloted the process of drawing up the gender transition service, has now disavowed his own reforms and said he regretted his involvement in the process. Other evangelical leaders have castigated the service as a "false gospel" which "denies the teachings of Jesus Christ".

But a spokesperson for the Church of England insisted the guidance had not changed the church's doctrine on sexuality or gender. "The guidance is not a restatement or a new statement on matters relating to gender, nor does it change the Church of England's teaching."

"The bishops will give the letter their serious consideration, especially in the context of the preparation of a major new set of teaching and learning resources on identity, relationships, marriage and sexuality which will be published next year."

Despite the huge outburst of opposition to the changes, many in the C of E want the church's hierarchy to move faster and further in affirming LGBT people.

The Revd Tina Beardsley, a transgender priest who helped draw up the new service, said opponents of the reforms were burying their heads in the sands by trying to delay churches holding services for their trans parishioners.

"It does seem a little strange to be saying 'I'm sorry but you've got to wait another two years and possible longer beyond that before we can actually pray with you'. That doesn't feel right to me."

Another trans priest involved in the process, Canon Rachel Mann, said she could not understand how anyone could object to the House of Bishops' guidance.

"This is a classic example of Anglican thoughtfulness. This is a set of guidance that addresses the deep human desire that we all have, whether trans or non-trans, to reaffirm our baptismal commitment to Jesus Christ," she said.