But if you refuse and rebel, you shall be devoured with the sword:
for the mouth of the LORD has spoken it.
Read Chapter 1
Fulgentius of Ruspe
AD 533
He who forgives sins is proclaimed to be just and merciful; we know with the greatest of ease that the forgiveness of sins is granted only to the converted, and the punishment of eternal damnation is inflicted only on those who remain in sin.…
In Isaiah is found a similar declaration from the divine Word against the recalcitrant who scorn the divine clemency. In this declaration it is made known that one obeys the divine commands not without reason and that one does not remain in evil without punishment.…
Who, I ask, is so hard and altogether inert that, in these words of the highest admonition, if he is not called to conversion out of the pleasure of what is promised, he is not at least compelled by the fear of punishment? Salvation will not accept the one who scorns the divine words, but the sword will devour him. - "On the Forgiveness of Sins 1.11.2–3"
Moreover, we know that even holy people have been given over bodily to Satan or to great sufferings on account of some slight sins. For the divine clemency does not permit the least blemish or stain to be found in them on the day of judgment. According to the words of the prophet, which are in fact God’s, he purges away all the dross of their uncleanness in the present so that he may bring them to eternity like fire-tried gold or silver, in need of no penal cleansing. - "Conference 7.25.2"
The phrase “the sword shall devour you” does not mean that sinners will be killed by swords but that God’s sword is the fire which is fueled by those who by their own volition do evil.… For were he to be speaking of a sword that cuts and immediately kills, he would not have said, “will devour.” - "First Apology 44"
