VATICAN CITY (AP) — Five conservative cardinals from Europe, Asia, Africa and the Americas have challenged Pope Francis to affirm Catholic teaching on homosexuality and female ordination ahead of a big Vatican meeting where such hot-button issues are up for debate.

The cardinals on Monday published five questions they submitted to Francis, known as “dubia,” as well as an open letter to the Catholic faithful in which they outlined their concerns.

The cardinals said they felt duty-bound to inform the faithful “so that you may not be subject to confusion, error, and discouragement.”

The letter and questions were first published on the blogs of veteran Vatican reporter Sandro Magister and Messa in Latino two days before the start of a major three-week synod, or meeting, at the Vatican. More than 450 bishops and laypeople are gathering behind closed doors to discuss the future of the Catholic Church following a two-year canvassing of rank-and-file Catholics around the globe.

Agenda items for the meeting call for concrete steps to promote women to decision-making roles in the church, including as deacons, and for ordinary faithful to have more of a say in church governance. It calls for a “radical inclusion” of LGBTQ+ Catholics and others who have been marginalized by the church, and for new accountability measures to check how bishops exercise their authority to prevent abuses.

The synod and its proposals for greater lay involvement have thrilled progressives and rattled conservatives who warn any changes could lead to schism. The cardinals are among those who have issued such warnings, and their questions to Francis asked him to affirm Catholic doctrine lest the synod undue the church’s traditional teaching.

In particular, they asked Francis to affirm that the church cannot bless same-sex couples, and that any sexual act outside marriage between man and woman is a grave sin. The Vatican teaches that homosexuals must be treated with dignity and respect but that homosexual acts are “intrinsically disordered.”

They asked him if the synod itself could replace the pope and bishops as the supreme authority in the church, an issue of concern to some in the hierarchy who feel threatened by the synod’s call for empowering lay people. And they asked him to affirm or deny if the church in the future could one day ordain women; church doctrine holds that only men can be ordained priests.

The letter and questions mark the latest high-ranking challenge to Francis’ pontificate and his reform agenda. The signatories were some of Francis’ most vocal critics, all of them retired and of the more doctrinaire generation of cardinals appointed by St. John Paul II or Pope Benedict XVI.

They were Cardinals Walter Brandmueller of Germany, a former Vatican historian; Raymond Burke of the United States, whom Francis axed as head of the Vatican supreme court; Juan Sandoval of Mexico, the retired archbishop of Guadalajara, Robert Sarah of Guinea, the retired head of the Vatican’s liturgy office, and Joseph Zen, the retired archbishop of Hong Kong.

Brandmueller and Burke were among four signatories of a previous round of “dubia” to Francis in 2016 following his controversial opening to letting divorced and civilly remarried couples receive Communion. Then, the cardinals were concerned that Francis’ position violated church teaching on the indissolubility of marriage. Francis never responded to their questions, and two of their co-signatories subsequently died.

Francis apparently did respond to this new round of questions penned by the five cardinals in April. The cardinals didn’t publish his reply, but they apparently found it so unsatisfactory that they reformulated their five questions, submitted them to him again and asked him to simply respond with a yes or no.

He didn’t, prompting the cardinals to make the texts public and issue a “notification” warning to the faithful.