They're innumerable. One of the most important would be that hurting other people and causing suffering violates my conscience, and makes it more likely that those things will be visited on myself, my family, and my country.
A guy told me the other day that he could think of no reason to tell me not to murder someone without appealing to the supernatural. Maybe you're of the same mind as he.
“One of the most important would be that hurting other people and causing suffering violates my conscience”
Mine too.
But what makes you or me the arbiter?
What if hurting others and causing suffering does not violate another’s conscious?