A coalition of conservative Catholic clergy and academics have accused Pope Francis of heresy, citing what they call overly liberal positions on topics like religious diversity, homosexuality and communion for divorced Catholics.

“We take this measure as a last resort to respond to the accumulating harm caused by Pope Francis’s words and actions over several years, which have given rise to one of the worst crises in the history of the Catholic Church,” the coalition wrote in a 20-page letter to the College of Bishops, published Tuesday by the conservative Catholic site LifeSiteNews.

{mosads}The letter singles out the 2016 papal document “Amoris Laetitia” (The Joy of Love) for special criticism. In the document, Francis called for making the Catholic Church more welcome toward “imperfect” members, such as divorced Catholics who have remarried in civil ceremonies.

Church law does not allow remarried divorced people who have not received an annulment to receive communion unless they abstain from sex with their current spouse. Francis called for flexibility on this doctrine, allowing priests and bishops to make case-by-case decisions.

The letter also lambastes Francis for saying Martin Luther’s intentions in sparking the Protestant Reformation “were not mistaken,” and for signing a joint 2016 statement with Lutheran leaders expressing gratitude for the Reformation’s “theological gifts.”

The group goes on to cite a statement this year between Francis and Ahmad Al-Tayyeb, the Grand Imam of Egypt’s Al-Azhar Mosque, saying religious pluralism is “willed by God.”

The letter was signed by 19 priests and scholars, the most prominent of which is Father Aidan Nichols, an English Dominican priest and theologian.

The Vatican did not immediately respond to a request for comment.