It is a sin to borrow, hence why Paul said, "be indebted to no one". And the Law of Moses forbade the Israelites from borrowing from the Gentiles, which is why the godly must not borrow from the ungodly. Lending at interest or engaging in usury is also a sin. Usury an unjust gain of money when one puts out money to try to gain predicated on chance/time, such as insurances, gambling, pensions, etc.