Exodus 22

Therefore the thief being taken pays fourfold, but he that spoils by violence is worse than if he steals. And if this last ought to give fourfold what he stole, the extortioner should give tenfold and much more. Even so he can make atonement for his justice. For of almsgiving not even then will he receive the reward. Therefore says Zaccheus, “I will restore what I have taken by false accusation fourfold, and the half of my goods I will give to the poor.” And if under the law one ought to give fourfold, much more under grace. And if this is so for one who steals, much more it is so for one who spoils by violence.

Homilies on the Gospel of Matthew 52.6

Some think that the precepts of the Old Testament are stricter than those of the New; but these are certainly deceived by careless consideration. For in the Old Testament, not avarice but robbery is punished. There, property unjustly taken is punished by fourfold restitution. But here this rich man is not blamed for taking what belonged to others, but for not giving what was his own. Nor is it said that he oppressed anyone by violence, but that he exalted himself in the things he had received. From this, therefore, we must especially conclude with what punishment he should be punished who seizes what belongs to others, if he is struck with the condemnation of hell who does not share his own possessions. Therefore let no one consider himself safe, saying: "Behold, I do not seize what belongs to others, but I enjoy things lawfully granted to me," because this rich man was not punished for taking what belonged to others, but because he wrongly abandoned himself to the things he had received.

40 Homilies on the Gospels, Homily 40

Some people give no thought to the question of demons, that is to say, to the fact that these demons, in order to be able to exist in the heavy atmosphere that encircles the earth, must have the nourishment of exhalations and consequently are always on the lookout for the savor of burnt sacrifices, blood and incense. Since they attach no importance to the matter of sacrifice, we would express ourselves also on this subject. If men who give sustenance to robbers, murderers and barbarian enemies of the great king are punished as criminals against the state, how much more will they be punished justly who through offering sacrifice proffer sustenance to the minions of evil and thus hold them in the atmosphere of the earth! And this holds true especially if knowing the text, “He that sacrifices to gods other than the Lord alone will be destroyed utterly,” they nevertheless sacrifice to these authors of evil on earth. In my opinion, when there is question of crimes committed by these demons operating against men, they who sustain them by sacrificing to them will be held no less responsible than the demons themselves that do the crimes. For the demons and they that have kept them on earth, where they could not exist without the exhalations and nourishment considered vital to their bodies, work as one in doing evil to mankind.

Exhortation to Martyrdom 45

In the law of the true God it is written, “He that sacrifices to gods shall be put to death, save only to the Lord.” The dreadful sanction of this command makes it clear that God wanted no sacrifices offered to such gods, good or bad.

City of God 19.21

There is a great deal about sharing and exchanging, but it is enough to say that the law forbids lending at interest to a brother. By brother it means not merely one born of the same parents but a member of the same tribe or one of the same faith, who shares in the same Logos. The law does not deem it right to collect interest on the capital. It seeks to enable free giving to those in need, with hands and minds wide open. God is the creator of this free gift. It is he who shares his goods, exacting as the only reasonable interest the most precious things human beings possess: gentleness, goodness, high-mindedness, repute, glory.

The Stromata Book 2

There is one bit of advice given to us by the ancient heathen Greeks, and by the Jews in the Old Testament, and by the great Christian teachers of the Middle Ages, which the modern economic system has completely disobeyed. All these people told us not to lend money at interest; and lending money at interest—what we call investment—is the basis of our whole system. Now it may not absolutely follow that we are wrong. Some people say that when Moses and Aristotle and the Christians agreed in forbidding interest (or 'usury' as they called it), they could not foresee the joint stock company, and were only thinking of the private money-lender, and that, therefore, we need not bother about what they said. That is a question I cannot decide on. I am not an economist and I simply do not know whether the investment system is responsible for the state we are in or not. This is where we want the Christian economist. But I should not have been honest if I had not told you that three great civilisations had agreed (or so it seems at first sight) in condemning the very thing on which we have based our whole life.

Mere Christianity, Book 3, Ch. 3 - Social Morality

It appears also that one who does not give back his pledge to a poor man stands condemned with God, for the following threat is directed against such a one: “He who does not receive back his pledge will cry to me,” says the Lord, “and I will hear him because I am compassionate.”[Of old] it was wicked and unlawful to gather the sheaves left after the harvest, or to glean the vines after the vintage or to gather up the olives that remain after the trees were picked, because these things were to be left for the poor. Now if this was commanded of those who were under the law, what shall we say of those who are in Christ? To them the Lord says, “Unless your justice abound more than that of the scribes and Pharisees, you shall not enter the kingdom of heaven.” .

It appears also that one who does not give back his pledge to a poor man stands condemned with God, for the following threat is directed against such a one: “He who does not receive back his pledge will cry to me,” says the Lord, “and I will hear him because I am compassionate.”[Of old] it was wicked and unlawful to gather the sheaves left after the harvest, or to glean the vines after the vintage or to gather up the olives that remain after the trees were picked, because these things were to be left for the poor. Now if this was commanded of those who were under the law, what shall we say of those who are in Christ? To them the Lord says, “Unless your justice abound more than that of the scribes and Pharisees, you shall not enter the kingdom of heaven.”

On Mercy and Justice

And Paul, earnestly beholding the council, said, Men and brethren, I have lived in all good conscience before God until this day. And the high priest Ananias commanded them that stood by him to smite him on the mouth. Then said Paul unto him, God shall smite thee, thou whited wall: for sittest thou to judge me after the law, and commandest me to be smitten contrary to the law? And they that stood by said, Revilest thou God's high priest? Then said Paul, I wist not, brethren, that he was the high priest: for it is written, Thou shalt not speak evil of the ruler of thy people. [Exodus 22:28]

“Brethren, I did not know that he was the high priest; for it is written, ‘You shall not speak ill of a ruler of your people.’ ” The mildness of this prompt reply shows how calmly he had spoken what he seemed to have uttered in anger, for such a reply could not be given by those who are angered or perturbed. And in the reply, “I did not know that he was the high priest,” he spoke the truth to those who understand him. It is as though he were saying, “I have come to know another High Priest for whose name’s sake I am suffering these injuries—a High Priest whom it is not lawful to revile but whom you are reviling, because in me you hate nothing else than his name.”

On the Lord’s Sermon on the Mount 1.19.58

Those emotions therefore which are morally good are the first fruits of our senses, whereas the others are of common and indifferent stock. This classification was used by Moses, following in that respect the language of the Jews, in his reference to the threshing floor of the law: “The tithes of your threshing floor and of your wine vat you shall not delay to pay: you shall give the firstborn of your sons to me.” All the morally good emotions of your senses are the first fruits of the threshing floor of the soul in such a manner as grain is separated in an actual barn floor.

Cain and Abel 2.1.5

The law says, “You shall not delay in offering your tithes and first fruits.” But grace says, “If you wish to be perfect, go, sell all that you have and give to the poor.”

Conference 21.32.3

Scripture says, “At least grant the offspring to its mother for its first seven days.” For if nothing comes to be without reason and milk flows in the mothers for the nourishment of the offspring, then in taking the offspring away from the providential endowment of milk, a person is doing violence to nature. So Greeks and anyone else who runs the law down ought to blush for shame if the law is generous over irrational beasts, whereas they actually expose human offspring to die. Yet for a long time with prophetic authority the law has cut short their ferocity through the commandment of which we have been speaking. For if the law refuses to allow the offspring of irrational creatures to be separated from their mother before taking milk, it is far more forceful in preparing human beings against that cruel, uncivilized view. If they ignore nature, at least they may not ignore the lessons of the law.

The Stromata Book 2