Dozens of Catholic priests and theologians have accused Pope Francis of heresy.
Francis is liberal by pope standards, and last year opened the door to accepting Catholics who have been through a divorce and remarried.
Traditionally, the Catholic Church views marriage as permanent - only death or an annulment ends it, and those who remarry outside of the church are technically committing adultery and cannot receive communion.
In 2016, Pope Francis issued an 'apostolic exhortation' entitled The Joy of Love, in which he said "no one can be condemned forever".
"Here I am not speaking only of the divorced and remarried, but of everyone, in whatever situation they find themselves."
More than 60 priests, theologians and academics have now issued a 'filial correction' - the first time such an undertaking has been taken since the 14th century, they said.
Francis is yet to respond, but the group who issued the 'correction' has been labelled a "tiny extreme fringe" Religious studies professor Massimo Faggioli told USA Today the group couldn't find a single cardinal or bishop to sign the document.
"The Catholic Church that has more than 200 cardinals now and more than 5,000 bishops - and they couldn't find one."
Technically they did find one - Bishop Bernard Falley of the Society of St Pius X - but Prof Faggioli said he doesn't count, because that group split from the Roman Catholic Church about five decades ago and until 2009, its leaders were excommunicated.
The letter was delivered to the pope a month ago, but the group decided to go public after receiving no response.