The present Open letter to the bishops of the Catholic Church goes a stage further in claiming that Pope Francis is guilty of the crime of heresy. This crime is committed when a Catholic knowingly and persistently denies something which he knows that the Church teaches to be revealed by God. Taken together, the words and actions of Pope Francis amount to a comprehensive rejection of Catholic teaching on marriage and sexual activity, on the moral law, and on grace and the forgiveness of sins. 
— Read on www.ncregister.com/blog/edward-pentin/father-aidan-nichols-signs-open-letter-charging-pope-francis-with-heresy