Lactantius — Divine Institutes 5.22

It would be long to bring forward all the kinds of virtue, that I may teach concerning each how necessary it is that the wise and just man be far estranged from those goods: by enjoying which, because the unjust enjoy them, the worship of the gods is believed true and effective. For the present question it is enough if from one virtue we prove what we intend. Certainly patience is a great and chief virtue, which alike the public voices of the crowd and the philosophers and the orators celebrate with highest praises. And if it cannot be denied that it is the highest virtue, it is necessary that the just and wise man be in the power of an unjust human, so that he may take on patience. For patience is the enduring with even mind of evils which are either inflicted or befall. Therefore the just and wise man, because he takes on virtue, has patience in himself: which he will wholly lack if he suffers nothing adverse. On the contrary, he who lives in prosperous things is impatient and lacks the greatest virtue: I call him impatient because he suffers nothing. He also cannot keep innocence, which itself is a virtue proper to the just and wise man, but he both harms often and desires what is another's and seizes by wrong what he has desired, because, empty of virtue, he is subject to vice and sin and, forgetful of frailty, swells with a mind insolently lifted. Hence the unjust and those who do not know God flourish in riches and power and honors. For all these are the rewards of injustice, because they both cannot be perpetual and are sought through desire and violence. But the just and wise man, because he judges all those human things — as Laelius said — his goods divine, desires nothing of another's, lest he hurt anyone at all against the right of humanity, nor desires any power or honor, lest he do injury to anyone — for he knows that all, generated by the same God and under the same condition, are joined by the right of brotherhood — but content with his own and with little, because mindful of his frailty, he seeks no more than whence to sustain life, and from that itself which he has had he also imparts to the one who has not, because he is pious; and piety is the highest virtue. Besides, he despises fleeting and vicious pleasures, for whose sake wealth is sought, since he is continent and conqueror of lusts. The same, bearing no swelling and insolence, does not lift himself higher nor raise a proud head, but is calm and agreeing and common and level, because he knows his condition. Since therefore he does injury to none nor desires what is another's nor even defends his own if they are taken by force, since he knows how to bear even an inflicted injury moderately, because he is endowed with virtue, it is necessary that the just human be subject to the unjust and that the wise be afflicted with insults by the foolish, so that both that one may sin, because he is unjust, and this one may have virtue in himself, because he is just.

But if anyone wants to know more fully why God allows the evil and unjust to become powerful, blessed, rich, and on the contrary suffers the pious to be lowly, wretched, poor, let him take up that book of Seneca whose title is 'Why many evils befall good men, though there is providence.' In which he has spoken many things not plainly by secular ignorance, but wisely and almost divinely. God, he says, holds humans as children, but he suffers the corrupt and vicious to live luxuriously and softly, because he does not think them worthy of his correction. But the good, whom he loves, he chastens more often and by continual labors trains for the use of virtue, nor does he allow them to be corrupted and depraved by fleeting and mortal goods. Whence it ought to seem wonderful to no one if for our faults we are often chastened by God. Indeed when we are vexed and pressed, then most of all we give thanks to the most indulgent Father, because he does not suffer our corruption to proceed further, but corrects by blows and stripes. From which we understand that we are a care to God, at whom, since we sin, he is angry. For though he could bestow both wealth and kingdoms on his people as he had given before to the Jews, whose successors and posterity we are, for that reason he willed that people to live under another's sway and command, lest corrupted by the happiness of prosperous things it should slide into luxury and despise God's precepts as those ancestors of ours did, who often, enervated by these earthly and fragile goods, wandered from discipline and broke the bonds of the law. He therefore provided how far he would grant rest to his worshipers if they had kept the commands, and yet would correct them if they had not obeyed the precepts. And so, lest they be corrupted by leisure as much as their fathers by license, he willed them to be pressed by those in whose hands he placed them, that he may both strengthen those slipping and restore the corrupted to fortitude and test and prove the faithful. For how can a commander prove the virtue of his soldiers unless he has had an enemy? And yet for that one an adversary rises against his will, because he is mortal and can be conquered; but for God, because he cannot be resisted, he himself raises up adversaries to his name, not who fight against God himself, but against his soldiers, that he may either prove or confirm the devotion and faith of his own, until by the blows of pressure he corrects dissolving discipline.

There is also another cause why he allows persecutions to be made against us, that God's people may be increased: nor is it hard to show why or how that happens. First many are driven from the cults of the gods by hatred of cruelty: for who would not shudder at such sacrifices? Next virtue itself and faith please some. Some suspect that the cult of the gods is not without cause thought evil by so many humans, that they prefer to die rather than do that which others do in order to live. Someone desires to know what that good is which is defended even unto death, which is preferred to all things that are pleasant and dear in this life, from which neither loss of goods nor of light nor pain of body nor torments of the vitals deter. These avail very much, but those causes especially have always increased our number: the surrounding people hears amid the very torments those saying that they do not sacrifice to stones made by human hand, but to the living God who is in heaven. Many understand this to be true and admit it into the breast. Then, as usually happens in uncertain matters, while they ask among themselves in turn what the cause of this perseverance is, many things that pertain to religion, published and caught by rumor in turn, are learned: which, because they are good, must please. Besides, the vengeance that followed, as always happens, drives strongly to believing. Nor is this a light cause either: that unclean spirits of demons, when license is received, plunge themselves into the bodies of many, from whom afterward, when they have been cast out, all who have been restored cling to the religion whose power they have felt. These so many causes gathered into one acquire a great multitude for God in a wonderful way.