Every nation on the face of the earth knows that it is evil to murder, to commit adultery, to steal, and to bear false witness, and knows that any country, state, or civilized society that did not forbid these evils would be doomed. No one thinks the Israelite nation was stupider than other nations and did not know these things were evils. Anyone might be amazed, then, that these laws, universally recognized on earth as they are, were delivered on Mount Sinai in such a miraculous way by Jehovah himself.
I have been told, though, that they were delivered in this miraculous way so that people would know that these laws are not only civil and moral laws but divine laws as well. Therefore to act against them would be not only doing something evil to our neighbor (meaning our fellow citizen and our community) but also sinning against God. When they were delivered by Jehovah on Mount Sinai, therefore, these laws became laws of religion as well. It should be obvious that whatever Jehovah commands, he commands as an aspect of religion; therefore his commands are something we need to follow for the sake of our salvation. Before I explain the Commandments, though, I will give a prefatory statement about their holiness, to show that they have religious import.
from True Christianity, Volume 1, Section 282