However this is, again, a highly problematic argument. The problem with engaging with 18th century thinkers on some of these issues is that our understanding of human evolution, early social interaction, history and other issues of reality has progresses a thousand times since then, and this invalidates many of his arguments.
Let's consider murder, for example, and take it as truth, for the purposes of the discussion, that basically every society on earth views murder, to differing degrees, as unacceptable (at least the indiscriminate killing of others within your society as a base line).
Now humanity is a biologically weak species, and our strength lies in our social bonds and relationships with other humans. It is this relationship and support network with those within our society that protects us from the dangers of rival species, and without this we are highly vulnerable to danger.
Since the development of early hominid societies, then, the continuation of our species has been invested in the continuation of such societal bonds, without which our safety net would break down and our species as a whole would be threatened. Thus, as early hominids developed, the idea that one should not commit an act that inherently breaks down the very bonds that form our sole barrier against the dangers of the natural world became so essential as to become ingrained in us.
This idea is so natural and so essential, when considered in a utilitarian sense, that when writing, speech and complex society became the norm, it is entirely natural that discourses of morality were developed that simply reflect the biological necessities which had been ingrained in our very existence for the past 190,000 years at the very least.
See where I'm coming from? There is no natural need to be told via discourses of religion that this behaviour is not moral, as the idea that it isn't moral is so deeply related to the fact that it is something that breaks down the fragment of society that keeps us safe, both as groups and individuals. In fact, these discourses of religion only reflect earlier discourses of morality that are drawn by early humans from their pensive interaction with the biological realities that they are encompassed by.