Ignoring the “judeo-Christian” answering your question: Lending without usury requires a method of profiting from the loan. Profit itself is not evil; it’s the means by which one makes the profit that can be. To achieve usury-free lending, one could offer a simple up front ratio - if you want to borrow ten thousand, you can either pay $800 up front or $1000 at the end of the loan. Additionally, lending would need to require specie for the amount lent, thus preventing artificial and inflationary lending. I would not be alllowed to borrow at a preferred borrower rate of $500 per $1000, incurring my own debt, and then passing on a worse ratio to you simply due to my better connections. Finally, debts must not be transferable. Since debt is the absence of wealth, it should not be classified as an asset, and therefore cannot be sold to another lender. By preventing the compounding of interest through transparent ratios, halting the practice of monetizing debt, as well as requiring that I cover all debts at time of lending with my own wealth promotes an honest system whereby the lender can reap profits for his risk and borrowers can trust their lenders based on square and clear terms and dealing.