Here's an old Q and A tidbit I found from Robert Sungenis, answering questions:
Question: I am particularly disturbed that at least from Innocent IV ( I am relying on memory here) onwards, and his bull "Ad Extirpande" in I believe 1234 A.D., torture was indicated to be permissible to use against heretics by the papal inquisition. In addition, many popes over the next three centuries then *mandated* that magistrates had to kill twice-convicted heretics by burning them at the stake, on pain of themselves being excommunicated and burnt themselves. This strikes me as particularly demonic and not particularly an example of the way of Christ who came to save sinners not destroy them, and I find it especially alarming coming as a series of commands in papal bulls.
Leo X in his bull "Exsurge, Domine" against Luther (1520) in point 33 condemns Luther for teaching that "burning heretics is against the Holy Spirit". Since Leo X is officially condemning Luther's *teaching* in this bull, it means Leo is *teaching* that burning of heretics is okay.
R. Sungenis: How about stoning of criminals and heretics in the Old Testament, under command of God? How about slaying women and children with the sword when conquering non-Jewish cities, under command of God?
Question: It is not until Pius XII, and later Vatican II, that we find the use of torture and such things as burning of heretics condemned. I believe Pope Nicholas may have condemned the use of torture against heretics c. 866 A.D., but the Medieval popes ignored this and ordered the opposite. I guess my main problem, Dr. Sungenis, is this: if the main purpose of the Pope is to be the rock-foundation of the Church, and to protect us against errors in faith and morals, then how could we have the agonizingly wrong-headed phenomenon of popes *commanding* that heretics be burned alive? That is not mere papal sin, it is rather commanding others to sin on pain of excommunication, and actually *teaching* that burning heretics is okay--and that must surely be a major error in teaching. (I can't think of anything more soul destroying than lighting on fire the flesh of another person and making them burn alive. I'd love your thoughts on these things.
And believe me, I write as a Lutheran who is, nevertheless, very well disposed towards the Catholic Church. I say the rosary, am most interested in Marian apparitions, and firmly believe in the Real Presence of the Body and Blood of Christ in the Holy Eucharist. Frankly, if the Bishop of Rome truly is the successor of Peter, I would want to honor him as such.
R. Sungenis: And look at the state of the Church when popes go to the opposite extreme of allowing evil to exist without punishing it. I personally would have no problem with reinstituting stoning for formal heretics and those convicted of capital crimes. If you don't like burning at the stake because it seems cruel, I'm sure there are other capital punishments that could be implemented to do the same thing that would be more acceptable to you and I in our culture.