The City of God

On the killings of men which are excepted from the crime of homicide. Chapter XXI

However, the same divine authority has made certain exceptions such that it is not permitted for a person to be killed. But these are excepted: those whom God commands to be killed, either by a given law or by a specific command to a person for a time. He does not kill who owes his service to the One commanding, just as a sword is a tool to the one who uses it. And therefore, they have in no way acted against this commandment, "Thou shalt not kill," who have waged wars by the authority of God, or who, holding the office of public authority according to His laws—which is the alternative: command. command of the most just reason—have punished the wicked with death. And Abraham was not only not blamed for the crime of cruelty, but was even praised for the name of piety, because he wished to kill his son, not wickedly, but obediently. And it is rightly asked whether it is to be held as a command of God that Jephthah killed the daughter who met him, when he had vowed that he would sacrifice to God whatever first met him upon his victorious return from battle. Nor is Samson otherwise excused for having crushed himself with his enemies by the ruin of the house, except because the Spirit, who performed miracles through him, had secretly commanded it. Therefore, with these exceptions—those whom either a just law generally commands to be killed, or God Himself, the fountain of justice, specifically commands—whoever has killed a person, either himself or anyone else, is caught in the crime of homicide.

That voluntary death can never pertain to greatness of soul. Chapter XXII

And whoever has perpetrated this upon themselves are perhaps to be wondered at for their greatness of soul, but are not to be praised for the soundness of their wisdom. Although, if you consult reason more diligently, not even greatness of soul is correctly named when someone, not being able to tolerate either whatever hardships or the sins of others, kills himself. For a weak mind is revealed, which cannot bear either the hard servitude of its body or the foolish opinion of the crowd. And a greater soul is rightly to be called that which can bear a wretched life rather than flee it, and can despise human judgment—especially that of the crowd, which is often shrouded in the darkness of error—above the light and purity of conscience. Therefore, if it is found in this greatness of soul, as they say of Cleombrotus, who, having read Plato’s book where he disputed on the immortality of the soul, threw himself from a wall and thus emigrated from this life to the one he believed to be better. For nothing was pressing him—no calamity or crime, whether true or false—that he could not bear, but only greatness of soul was present for the sake of seizing death and breaking the sweet chains of this life.