Fair enough. So lets get to the crux of the issue. Is usury in any form a mortal sin?
Some of our most recent popes (and the Catechism) talk about usury as a serious sin. I’m not sure about “mortal” sin, though.
From Pope John Paul II, Address to the Members of the National Council of Anti-Usury Foundations (1999): I know well, dear friends, the difficulties that you face. But I know that you are determined and united in fighting
this serious social evil. Continue to combat usury, giving hope to individuals and families who are its victims. The Pope encourages you to pursue your generous work to build a more just society, one of solidarity, and more attentive to the demands of the needy. From Pope John Paul II, General Audience (4 February 2004): Finally, three final precepts are listed for our examination of conscience: to be faithful to our word and to our oaths, even in those cases where the consequences will be detrimental to us;
not to practice usury — a plague that is a disgraceful reality even in our days that can place a stronghold on the lives of many people; and finally to avoid all corruption in public life, another commitment that we could also rigorously practice in our time . . . From Pope John Paul II, General Audience, (10 Nov 2004): The first false god [is] the violence which humanity unfortunately continues to resort to even in these bloody days,. . . Accompanying this idol is an immense procession of wars, oppression, perversions, torture and killing, inflicted without any trace of remorse. . . . the second false god is robbery which is expressed in extortion, social injustice,
usury, political and economic corruption. From the Compendium of the Social Doctrine of the Church §323 and 341 (2004): The prophetic tradition condemns fraud,
usury, exploitation and gross injustice, especially when directed against the poor . . .
Although the quest for equitable profit is acceptable in economic and financial activity, recourse to usury is to be morally condemned: “Those whose usurious and avaricious dealings lead to the hunger and death of their brethren in the human family indirectly commit homicide, which is imputable to them”.[714] This condemnation extends also to international economic relations, especially with regard to the situation in less advanced countries, which must never be made to suffer “abusive if not usurious financial systems”.[715]
More recently, the Magisterium used strong and clear words against this practice, which is still tragically widespread, describing usury as “a scourge that is also a reality in our time and that has a stranglehold on many peoples’ lives”.[716] From the Compendium to the Catechism of the Catholic Church §508 (2005): 508. What is forbidden by the seventh commandment?
Above all, the seventh commandment forbids theft, which is the taking or using of another’s property against the reasonable will of the owner. This can be done also by paying unjust wages; by speculation on the value of goods in order to gain an advantage to the detriment of others; or by the forgery of checks or invoices. Also forbidden is tax evasion or business fraud; willfully damaging private or public property;
usury; corruption; the private abuse of common goods; work deliberately done poorly; and waste.From Pope Benedict XVI, General Audience (2005): The heart of this fidelity to the divine word consists in a fundamental choice of charity towards the poor and needy: ‘The good man takes pity and lends … Open-handed, he gives to the poor” (vv. 5, 9). The person of faith, then, is generous; respecting the biblical norms, he offers help to his brother in need, asking nothing in return (Deuteronomy 15: 7-11), and without falling into the
shame of usury, which destroys the lives of the poor.’ From the Catechism of the Catholic Church, §2269 (1993): The acceptance by human society of murderous famines, without efforts to remedy them, is a scandalous injustice and a grave offense. Those whose
usurious and avaricious dealings lead to the hunger and death of their brethren in the human family indirectly commit homicide, which is imputable to them.