If you are not Catholic, and even if you are, you could be forgiven for not knowing that a remarkable event is unfolding in Rome.

This week, Pope Francis convened an “extraordinary synod of bishops” and laypeople, only the third gathering of its kind in history.

The topic of discussion is marriage and family, which sounds tame enough.

But the churchmen and their guests will spend the two-week meeting delving into all that marriage and family entail in the modern era — which requires addressing issues considered increasingly acceptable in larger society but still taboo among Catholics — like premarital sex, divorce and same-sex marriage.

During his opening remarks, the pope called for openness among participants. His expressed desire was to create an environment where all attendees are free to “speak boldly,” to voice even heterodox opinions without censure or fear. All perspectives are considered with respect and humility.

That in itself is extraordinary. Imagine getting such a reception during a political debate.

And early reports from the synod suggest that attendees are taking the pontiff at his word. While the Vatican is releasing only limited information about what the bishops are saying, it is more readily sharing commentary by the 12 married couples that also are taking part in the discussions.

One couple relayed the struggles faced by their devout Catholic friends with a gay son; another couple described the hurdles they confronted trying to start a fellowship organization that would cater to couples in “irregular situations,” such as divorced and remarried partners who did not seek an annulment or unmarried couples who are living together.

Those issues may not seem like a big deal to many in contemporary society, but how to address them in a manner that is both charitable and faithful to church doctrine will require the courage of the prophet Daniel and the grace of, well, Jesus Christ himself.

There is no doubt that the church teaches some difficult truths about life and the nature of man, many of which are unwelcome (to say the least) in a culture that is increasingly self-indulgent and secular.

But many people come to and stay in the church not because what it teaches is easy. Quite the contrary. They come prepared to carry a cross. As New York Timescolumnist Ross Douthat explained so eloquently, “most people understand the point that mercy can in some cases be offered too cheaply, whether by a religious authority or by the wider culture, in a way that doesn’t just lift loads from people’s backs, but effectively encourages them to wear their moral obligations much more lightly than they should.”

That perspective is shared by Louise Mensch, a divorced and remarried Catholic who willingly abides by church teaching not to receive Holy Communion. She wrote in the British publication The Spectator that “the Church, while it strives to emphasize mercy, cannot do so by encouraging sin.”

Many progressive Catholics, inspired by Francis’ pastoral nature and candid remarks (“Who am I to judge?”), were encouraged that his papacy might signal a dramatic shift in church doctrine. And what better place to begin the transformation than with a gathering to address one of the most debated church teachings — the indissolubility of marriage.

But no such shifting will occur. “What’s being discussed at this synod are not doctrinal issues, but the practical ones,” said Hungarian Cardinal Peter Erdo, the synod’s “relator.” The bishops seem keenly aware that divorce often means an abandoned spouse and vulnerable children.

That core doctrines are off the table should not surprise, nor disappoint, any Catholic.

After all, doctrine is, by definition, immovable. There is inherent danger in the attempt by some to “soften” teachings that have endured for millennia — because of their likely ripple effect. As Mensch explains: “Theologically, the Church is like a giant tower in Jenga; pull out one brick and you topple all the others.”

The church has endured for so long because it is unchanging. Still, it has much to learn about how to better relay its sometimes challenging teachings in a culture whose moral thermostat is no longer set to automatically be receptive to the teaching that marriage is for life, period.

That is what this synod is intended to accomplish.

And taking on this task with open minds and hearts is truly extraordinary.

Cynthia M. Allen is a columnist for the Fort Worth (Texas) Star-Telegram.