You shall not steal. (Exodus 20:15)
We should fear and love God that we may not take our neighbor's money or property, nor get them by false ware or dealing, but help him to improve and protect his property and business [that his means are preserved and his condition is improved]. (Martin Luther)
No theft, check. No fraud, check. Done? Well, let's slow down. We'll get to the “heart” of theft in a couple of days, but let's think about this a bit more.
With this commandment, God recognized and ratified property, private property, as valid in society. Elsewhere in the Law of Moses, various types of property are recognized – things and what we would now call real estate (i.e, land) – with consequences specified for the theft thereof.
Further, in applying this commandment, the Law of Moses also ratifies the validity of private business. Under the rubric of forbidding false weights and measures, businesses are forbidden to deal fraudulently. Honest trade and dealing are thereby validated. And what should be made of God not limiting prices or profits from trade? Did God forget something? Or was God leaving such matters – other than where fraud is involved – to the vagaries of conditions such as people's desires and scarcity?
Let's take this in another, possibly scary, direction. This commandment, this law, comes from God. Human beings are subject to it – individual, businesses and institutions … including ... governments. What would theft by a government look like? Uncompensated taking of property would obviously be theft by government. As would forbidding usage of property without compensation. What about taxes? Well, taxes pay for services government provides, so taxation would not intrinsically be theft. But, here's where it gets scary and even more political – acknowledging the validity of private property and private business is already political, given modern political thinking. What about taxing “the rich” at a higher rate, because the rich “can afford it”? The Law of Moses mandated equality in justice for “the poor” and “the rich” alike – Exodus 23:3 and Leviticus 19:15. If a “rich” person uses government services more than does a “poor” person, that “rich” person should pay more, in proportion to their usage of those services. But for government to tax a “rich” person at a higher rate because “the rich” “can afford it” is to hide government theft behind euphemistic smokescreen.
What about that part in Luther's explanation, “... but help him to improve and protect his property and business ...”? In this, Luther was applying Exodus 23:4-5, “If you meet your enemy's ox or his donkey wandering away, you shall surely return it to him. If you see the donkey of one who hates you lying helpless under its load, you shall refrain from leaving it to him, you shall surely release it with him”. This commandment, like others, has a positive upside. However much we might dislike a person we help in this manner, the benefit such kindness brings to society – kindness begetting kindness – is incredible. And who knows what relationship changes that might bring between the two enemies? Getting back to actual theft and fraud, honesty – personal and in business – is a necessity for society to function.