Ok, here's an arguement. The bible and it's god are left out because the bible is hopelessy flawed and it's god, if it exists, is mute and inactive.
The universe appears to be evolving, and to have evolved from a lower level of simplicity to higher levels of complexity. Evolution on the earth, likewise. The human brain, w the nervous system, is the most complex object in the known universe, or at least in the solar system. The harmonious thing, the 'right' thing to do seems to help it along in it's growth, increasing it's complexity, to help it's upward evolution. In doing so, however, it seems like the right thing to do is to respect the relative values of other living and inanimate things in their own evolutionary paths.
Helping the brain/mind evolve would entail many, many types of processes; emotional, knowledge, freedom to explore, freedom to think any thought possible without hindrance, pruning of false data, ...
There are some glitches to this paradigm, though. For instance, why the massive extinction (70%) just before the age of the dinosaurs. Then of course, the extinction of the dinosaurs themselves. However, it could be that they were mistakes that heeded to be displaced. Then again, nothing lasts forever, not even humans. Flukes seem to happen.
See? Good and evil don't exist. We are just a link in a chain of development from the past into the future. Wrong/negative turns/decisions are just paths that are explored and discarded, generally, although sometimes it takes a long time. But they do increase the knowledge base.
SS