All of the things we consider immoral or wrong are considered wrong because they are detrimental to a functioning group. Humans are a social animal...just like any other species, there are certain actions that harm or impede group cohesion and function. The only difference between human society and behavior and any other social species is the nature of the "rules" of acceptable behavior, their exceptions and the "punishment" for transgressions of those rules.
While "natural law", as a philosophy is largely Greek, and was adopted by the early Catholic Church (and subsequenly adopted by most Protestant denominations), it is fairly universal--which totally makes sense as human nature is universal... Which is why the fundamental underlying ideas of most religions are fairly universal--and at the heart of all of them, the idea of treating others as one wishes to be treated...
at 6:19 PM on Oct. 9, 2008