Could the Law of Moses stop a person from stealing or committing adultery?
The Law of Moses had no power to stop a person from stealing or committing adultery. Scripture shows the Mosaic Law was faulty from mankind's perspective because man could not keep it, and it provided no help to obey. Its function was to condemn, not to empower righteousness. The indwelling Spirit makes the difference under the New Covenant.
Les teaches from Hebrews 8 that the first covenant, the Law of Moses, was not faultless from mankind's perspective. If it had been faultless, there would have been no place sought for a second covenant. He explains that it was perfect from God's perspective, but not from mankind's, because man could not keep it. The Law had no power to help mankind keep the Law; it had absolutely no power to keep a man from stealing, committing adultery, and the like. All it could do was condemn him. By contrast, Romans chapter 8 presents living under the Law of the Spirit, and the Spirit indwells believers, as also seen in I Corinthians 3 and 6.