A Croatian nationalist and a fascist, he combined religion with his political ideology. In one instance, in a 1942 raid on the Serb Orthodox villages of Drakulici, Sargovac and Motika, he slashed the throat of a child and exclaimed: "Ustasha, this is the way in which I baptise these bastards in the name of God. You should just follow my example. Let this thing be on my soul, but I am going to give you my forgiveness and the forgiveness of the Church for your acts." At his trial for war crimes, he later admitted to personally killing at least one hundred people, including children, per day in the camp.
A Croatian doctor who resisted the Ustashe, Dr. Nikolic, a prisoner at Jasenovac spoke about his first meeting with Filipovic: 'His voice had an almost feminine quality which was in contrast with his physical stature and the coarseness of his face... I was hardly seated, and as I sank into my sad thoughts, I heard the orders 'Fall in-Fall in!'... An old Ilija, an Ustasha, appeared in the threshold of the hut, a revolver in one hand and in the other, a lash ... Before us passed six men, their hands tied before their backs with chains. The Ustashe had their revolvers loaded and aimed. 'Fra Sotona' (Filipovic) walked over and approached our group. 'Where is our new doctor?' I knew he meant me. 'He is here,' someone replied. He came a little nearer, looking at me with an insolent, ironic, bizarre manner. 'Come here, doctor,' he said, 'to the front row, so that you will be able to see our surgery being performed without anesthetic. All our patients are quite satisfied. No sighs, nor groans can be heard. Over there are the head and neck specialists, and we have need of no more than two instruments for our operations.' 'And Fra Sotona caressed his revolver with one hand and his knife with the other ... Looking at these victims who, in a few moments would be in another world, fear written on each face, no one could penetrate the depth of their moral abyss. They silently watched the gathering crowd of more pitiful people, more condemned people like themselves. Fra Filipovic approached a group of them. Two shots rang out, two victims collapsed, who began to twitch with pain, blood surging from their heads intermingling with the brain of one or the eyes of the other. 'Finish off the rest!' cried Filipovic to the executioner as he put his revolver away.'
After the war, Filipovic-Majstorovic was tried and sentenced to death. He was hanged wearing the friar's robes he often wore in the camp, when giving confession and murdering prisoners.