The letter shows the real division is not pro- and anti-Francis, or rigorism versus mercy, but over Church teaching

In the three and a half months since its publication, the Pope’s exhortation Amoris Laetitia has been described as brilliant, erroneous, confusing, groundbreaking and unremarkable. It has opened up divisions – but what is at the heart of those divisions may be something deeper than the usual to-and-fro of Church politics.

Now a group of Catholic scholars and clergy have made the most serious intervention yet. It isn’t quite right to call it a “challenge”, because the theologians wrote – in a letter to cardinals seen by the Catholic Herald – that they neither accused the Pope of teaching heresy, nor thought the document unambiguously contradicted Church teaching.

It’s the ambiguity that’s the question: the signatories of the letter – who include some highly distinguished names, including Fr Aidan Nichols – say that they fear a “natural reading” of the text will lead Catholics into error.

To take one of the 19 passages cited in the letter, this paragraph could be read in several different ways:

It … can no longer simply be said that all those in any ‘irregular’ situation are living in a state of mortal sin and are deprived of sanctifying grace. More is involved here than mere ignorance of the rule. A subject may know full well the rule, yet have great difficulty in understanding ‘its inherent values’, or be in a concrete situation which does not allow him or her to act differently and decide otherwise without further sin.

“Irregular” is not defined – though the reader will probably infer “a sexual relationship outside a valid marriage”. Also ambiguous is “More is involved here”: clearly in any human situation, there are many things “involved”, so what is the sentence adding? Is it dropping a hint? Again, “decide otherwise” – otherwise than what?

You can make yourself dizzy trying to solve these conundrums. But the theologians’ letter, without claiming to have discerned a single meaning in the text, simply explains what would be an untenable reading: “that a person with full knowledge of a divine law can sin by choosing to obey that law”.

That would conflict with established Church teaching, from Scripture to the Council of Trent to Veritatis Splendor.

As with the other passages, the theologians are asking cardinals to ask the Pope to rule out such an interpretation.

Joseph Shaw, the group’s spokesman, has said: “It is hardly controversial that the document is being read in widely different ways, some of them quite at odds with the perennial teaching of the Church.”

But others argue that we shouldn’t be picking over the document. The theologian Pia de Solenni, associate dean at the Augustine Institute, tells me that although the ambiguities are “problematic”, “we have a 2000-year tradition that clarifies any ambiguity. In my opinion, our time would be better spent constructively working to strengthen marriage.”

Isn’t the document already being misinterpreted, though? “Sure, some will use one opportunity to advance their own agenda,” says de Solenni. “But that’s when the Church (not just the hierarchy) needs all the more to articulate and live clearly Church teachings.”

The need to show Catholic truth in deeds as well as words is itself a major theme of Amoris Laetitia. The letter’s signatories, for their part, say the truth cannot properly emerge unless it is distinguished from false readings. One of the signatories, the seminary professor Alan Fimister, says he is “constantly approached by people citing this or that passage of Amoris Laetitia and asking how it could be reconciled with the faith as they have received it”.

His usual reply is that various authorities say Amoris Laetitia is not magisterial teaching. “But this still leaves the impression that it would be acceptable to hold the heretical ideas attributed to Amoris Laetitia even if they are not being directly taught… and it isn’t.”

Is Pope Francis likely to respond by issuing a clarification? The Pope has previously backtracked after criticism: he removed a comment about invalid marriages from an official transcript, and said his remarks about Ukraine, made in a landmark joint statement with Patriarch Kirill, were “debatable”.

Having said that, Francis has not been inclined to discuss the exhortation in depth: asked about perhaps the most-discussed sentence in the text, he said he couldn’t remember it.

Francis has said that the best interpreter is Cardinal Christoph Schönborn. But Cardinal Schönborn’s various remarks have themselves been subject to very different interpretations, so the ambiguity has not been resolved.

That is one great virtue of the theologians’ letter: it makes plain what is and isn’t at stake. Catholics may be misled about doctrine, the letter says – and these are the doctrinal issues which need to be clarified.

That suggests that the real dividing line is not between pro-and anti-Francis, or rigorism versus mercy, but over Church teaching. Regardless of whether the cardinals do appeal to the Pope, and whether he issues the requested clarification, a new benchmark has been set for theological debate about the document.