The Bible does make it clear that the prohibition of usury was part of the Moral Law, not the ceremonial law, or civil law. Why?
The ceremonial law is law of which obedience to was a foreshadowing of the Messiah, who would save the Nation of Israel from their sin. The most obvious example would be the giving of sacrifices which symbolised the need for bloodshed for their be forgiveness of sins (Hebrews 9:22). The civil law is law which set out how sins was to be punished, and administered by God's appointed judges. Execution of murderers and adulterers are examples of civil law.
The Moral Law of God, however, is different from the ceremonial and civil law of the Mosaic Law. The Moral Law of God is one that is Eternal, written on the hearts of all people, whether Christian or not (Romans 2:15). It applies to all people, and all people know they disobey it when they are confronted with it. They know it in their conscience.
Why does the modern western Church find it so hard to understand why usury is sin?
The modern western Church has failed to understand exactly what it means to truly expose and fight sin. Truly exposing sin and fighting sin is now seen as too aggressive, militant, or not necessary by the typical modern Christian, including the conservative ones. They may say that agree with speaking truth and the God is true, not humans, but, that it is not up to the Church to fight sin where it forces others to change their whole mindset and lifestyle. No, this itself is a perversion of truth, a deviation from truth.
The Church is not just to merely change a person's mind on an issue, but to by all means seek the punishment of the evil, such as usurers, child-sacrificers, known as "abortionists", homosexuals, cannibals and those who promote evil ideologies, such as liberalism, the homosexual agenda, atheism, feminism and religious cults. The role of the State who is ordained by God to punish evil in the eyes of God. Government, not matter what the world thinks, is to punish evil in the eyes of God. This is made very clear in Romans 13:1-7:
Let every soul be subject unto the higher powers. For there is no power but of God: the powers that be are ordained of God. Whosoever therefore resisteth the power, resisteth the ordinance of God: and they that resist shall receive to themselves damnation. For rulers are not a terror to good works, but to the evil. Wilt thou then not be afraid of the power? do that which is good, and thou shalt have praise of the same: For he is the minister of God to thee for good. But if thou do that which is evil, be afraid; for he beareth not the sword in vain: for he is the minister of God, a revenger to execute wrath upon him that doeth evil.
Wherefore ye must needs be subject, not only for wrath, but also for conscience sake. For for this cause pay ye tribute also: for they are God's ministers, attending continually upon this very thing. Render therefore to all their dues: tribute to whom tribute is due; custom to whom custom; fear to whom fear; honour to whom honour.
You may say, exactly, it means be subject to the Law of the country you live in. You are saying that the government should not punish evil for being evil? You think government should not punish usury or homosexuality, but to punish murder, A government which does not punish evil, whether it be a cult, usury, feminism, child sacrifice, called "abortion", homosexuality is a wicked one. Any government which even tolerates such evils is wicked.
The doctrine of "separate of Church and state", means that the State and the Church should not cooperate with each other. What is truly means is that the State should have its own laws that it wants, and has a "right" to reject, pervert, twist, or selectively choose certain Moral Laws of God that its likes to enforce. To Hell with "separation of Church and State"! To Hell with the belief that government can make the laws it wants, selectively those Moral Laws it appreciates, which protect selfish individuals from losing what they do not want to lose - their lives, spouses, or money, but yet think government should totally reject other Moral Laws of God such as the Law against usury, and homosexuality.
Usury is sin, no matter what government thinks, or what many Christians think. It is a sin that breaks the Moral Law of God. Here is what Scripture says about usury:
Thou shalt not give him thy money upon usury, nor lend him thy victuals for increase (Leviticus 25:37).
He that hath not given forth upon usury, neither hath taken any increase, that hath withdrawn his hand from iniquity, hath executed true judgment between man and man (Ezekiel 18:8).
Hath given forth upon usury, and hath taken increase: shall he then live? he shall not live: he hath done all these abominations; he shall surely die; his blood shall be upon him (Ezekiel 18:13).
In thee have they taken gifts to shed blood; thou hast taken usury and increase, and thou hast greedily gained of thy neighbours by extortion, and hast forgotten me, saith the Lord GOD (Ezekiel 22:12).
He that putteth not out his money to usury, nor taketh reward against the innocent. He that doeth these things shall never be moved (Psalm 15:1,5).
Usury is not merely an act of greed, the indulgence of the one's wants (Ezekiel 22:12), or merely extortion. Usury itself is the worship of mammon. It is to seek gain, not from the God-ordained way of labour, but from the debt-slavery of others. It is the spiritual manipulation of borrowers who are in bondage to debt, and charged for borrowing money.
Usury is a perversion of God's order that lending is to be done freely, and that the borrower is to repay his debts. Deuteronomy 15:8 says: "But thou shalt open thine hand wide unto him, and shalt surely lend him sufficient for his need, in that which he wanteth". This describes the God-given order at to how one should give, not applicable only to one's own brother or sister, but also to the stranger, that is, anyone else. That the Bible does not distinguish between a personal loan and business loan does not justify usury being charged by businesses. By no means! That one should lend freely is by no means to justify the failure of a borrower to repay his debts. By no means! The wicked man borrows and does not repay, but the righteous one is gracious and giving (Psalm 37:21).
The obligation that God ordains for debtor and creditors respectively is one that must be obeyed for lending to be just, righteous and equitable. Both have their responsibilities, and only then can finance be just, righteous and equitable.
As long as society tolerates usury and non-repayment of debts, the whole society will continue to be in the financial chaos it is in now. Only the Church who has the answers to this problem which is a spiritual one, can seek righteousness and justice by pushing to ban usury at all levels, from the personal level to the State level. However, the Church is deep asleep, in a delirium about usury, even thinking that usury is good and righteous.
Regarding absolutely any moral or spiritual issue, of which usury is one, as long as the Church tolerates some evil, by the failure to totally abolish it from society, and seek punishment of all evils, it will take root and grow.
The problem lies with the Church who is a blind as a bat about usury, in a delirium as to its evil.
O Church, Bride of Christ, when will you wake up out of your slumber? When will you pick up your sword and fight all evils?