Snorri1234 wrote:So we're back with the assumption that good and evil can only come from God?
I think that would be wrong to assert. It would be better to assert that in the end good and evil are postulates, we can "assume" them but we cannot logically derive them in a way that we can prove. Just like the "parallel postulate" it's a wonderful tool for the here and now which may not be true in all possible cases. (Like non ecludian geometry.)
The best idea of "good"/"evil" that I've seen came from a Dragon magazine article back when the 2nd Edition of AD&D by TSR was still being played. (For those not familiar with gaming D&D is now in 4th edition and is owned by Wizards of the Coast - WoTC.)
Evil was defined as the persuit of the goals of self in opposition to the goals of others.
Good was defined as the persuit of the goals of others in opposition to the goals of self.
Thus happiness would be seen as a "goal" but not the only goal.
You don't really need a god to define this but there is no force other than just assumption. In one sense morality isn't really a "science." It's more of an art.