Spiritual war is intensifying in Rome over issues such as marriage and divorce, homosexuality and contraception, it has emerged.
In the letter, written in English, the cardinals warn: "Various fathers have expressed concern that a synod designed to address a vital pastoral matter – reinforcing the dignity of marriage and family – may become dominated by the theological/doctrinal issue of Communion for the divorced and civilly remarried. If so, this will inevitably raise even more fundamental issues about how the Church, going forward, should interpret and apply the Word of God, her doctrines and her disciplines to changes in culture.
"The collapse of liberal Protestant churches in the modern era, accelerated by their abandonment of key elements of Christian belief and practice in the name of pastoral adaptation, warrants great caution in our own synodal discussions."
The letter, written last week but only now made public, appears to have been what prompted the Pope to issue his own indirect warning against conspiracy theories.
The influential Jesuit priest who is at the synod, Father Antonio Spadaro, tweeted:
The confusion is reflected in some of the reports from the different groups. There are four English language groups, and these reports were summarised by the Irish Times which illustrated how the synod fathers appear to feel lost and lacking in direction. They are in groups to help draft a final document from the synod but they appeared to have little understanding of what this document should contain or who it will be aimed at.
One group, chaired by Cardinal Thomas Collins of Canada, did not undertand who their intended audience is. "In other words, are we writing to the Holy Father, to the families of the church, or to the world?" he asked.
The group chaired by Archbishop of Armagh Eamon Martin wrote: "We have been somewhat uncertain about the task presented to us... at times our work has seemed more muddled than methodical."
Archbishop of Dublin Diarmuid Martin, secretary of a third group, told The Irish Times: "I have no idea myself what way the synod is going to go. We're writing a document, or contributing to the writing of a document. We don't know who it's being written for. Is it written for the pope?"
A fourth English language group warned against an "overly Euro-centric or Western mindset" and an excessively bleak view of contemporary family life.
In response to the concerns, Catholic commentator John Allen is describing Pope Francis as "shock therapy" for the Church. "Catholics just aren't used to seeing differences among their leaders play out so publicly and, at times, with such a sharp edge," he writes. "A fundamental clash remains between those who believe in outreach and dialogue, meeting people where they are, and those worried that the Church must not lose its capacity to call sin by its real name."