According to Romans 7, what is a lost person under?
A lost person is under the demands of the Mosaic law, the Ten Commandments. Whether they admit it or not, they are under God's anathema when they violate the law, and they cannot escape it. They will be judged according to that law at the great white throne.
Les explains that just as a spouse is freed from the marriage law when the partner dies, so the lost person is under the demands of the Mosaic law, the Ten Commandments. He says the lost person is under the very anathema of God for adultery, stealing, killing, or anything contrary to the law. Even an atheist cannot escape those commandments; they hang over him. Les warns that at the great white throne, the lost will be judged according to that law. The law is perfect, righteous, holy, and eternal, not merely Old Testament stuff. To come out from under that demand, one must die—not physically, but in the old Adam.