“When you are assembled, and my spirit is present, with the power of our Lord Jesus, you are to deliver this man to Satan for the destruction of the flesh, that his spirit may be saved in the day of the Lord Jesus.” – St Paul

“Those that corrupt families shall not inherit the kingdom of God. If, then, those who do this as respects the flesh have suffered death, how much more shall this be the case with any one who corrupts by wicked doctrine the faith of God, for which Jesus Christ was crucified!” – St Ignatius of Antioch

“No mortal sins more grievously than do the heretics who deny Christ after they have known Him.” – St Bede

“[T]he spirit of error and lying hath taken his wretched soul with him straight from the short fire to the fire everlasting … the devil’s stinking ‘martyr'” – St Thomas More

“[The heresiarch] should meet with no mercy: he assumes the office of the Tempter; and, so far forth as his error goes, must be dealt with by the competent authority, as if he were embodied evil. To spare him is a false and dangerous pity. It is to endanger the souls of thousands, and it is uncharitable towards himself.” – St John Henry Newman

“If in order to save an earthly life it is praiseworthy to use force to stop a man from committing suicide, are we not to be allowed use the same force — holy coercion — to save the Life (with a capital) of many who are stupidly bent on killing their souls?” – St Jose Maria Escrivá