Pope Francis has signalled that he is preparing to canonise Father Jacques Hamel, the French priest murdered by two Islamist terrorists in July.
Father Hamel could be made a saint without needing miracles because he died a Christian martyr.
The pope, who has been declared a top target himself by Islamic State, said the Islamist terrorists were satanic.
He was preaching this morning in St Marta's chapel at a mass for Father Hamel at St Marta's chapel in the Vatican to a group of 80 pilgrims from the Diocese of Rouen, who were there with the Archbishop of Rouen Dominique Lebrun, who has recently stated his own desire to see Father Hamel declared a saint.
Father Hamel was murdered on July 26 in the church of Saint-Etienne-du-Rouvray.
Pope Francis said: "Father Jacques Hamel has been slaughtered in the Cross, just as he celebrated the sacrifice of the Cross of Christ.
"A good man, meek, a brother, who was always trying to make peace, was assassinated as if it were a criminal."
This was a feature of satanic persecution, the pope said, speaking on the Feast of the Cross of Jesus Christ.
He said it was clear that Father Hamel saw his martyrdom coming while he was there, at the altar, and accepted it: "He gave his life for us, he gave his life not to deny Jesus. He gave his life in the same sacrifice of Jesus on the altar and from there he accused the author of persecution: 'Go away, Satan!'"
Pope Francis spoke of the current growth in Christian persecution. "Today there are Christians murdered, tortured, imprisoned, slaughtered because they do not deny Jesus Christ. In this story, we come to our Père Jacques: he is part of this chain of martyrs. Christians who today suffer - either in prison or the death or torture - not to deny Jesus Christ, they show precisely the cruelty of this persecution."
It was satanic, he said, and martyrs are blessed. "We must pray to him, to give us meekness, brotherhood, peace, even the courage to tell the truth: to kill in the name of God is satanic."
Christian Today reported that Archbishop Lebrun is launching a cause for the canonisation of Hamel which he hopes will be fast-tracked. Archbishop Lebrun said recently: "The death of Father Jacques Hamel is the ultimate testimony of his faith in Jesus, he affirmed to the end. The holiness of recognition procedure... can not begin until five years after the death of the person. Formally, it is the bishop of the person's place of death to initiate the procedure. There is a local phase with a careful survey of the life and death of the person. Then the case is sent to Rome where [it is] studied before the Pope's decision."