How did we come by this “fallen nature” in your scenario?
Creation is by nature incomplete, and sin is related to incompleteness, need, desire, jealousy. It took millions of years from the Big Bang until the first generation of stars, and tens to hundreds of millions of years to the gravitational collection of galaxies. It took yet further billions of years until the first generation of stars–which had generated the heavier elements in their cores through the process of nucleosynthesis-- exploded these element into the interstellar medium, where they collected gravitationally into accretion discs that become second generation stars with rocky, potentially life-bearing planets.
On planets with suitable chemical, thermal, geological, and meteorological conditions, life was created. When life evolves under conditions of finite resources (as it must on any finite planet), there will always be predation and competition for resources and for ecological niches. Prior to the evolution of consciousness, under “premoral” conditions, predation and competition are not moral issues; a lion is not sinning by tearing apart a gazelle. However, when
Homo sapiens evolved consciousness, they became aware of the possibility of acting otherwise. Actions which among non-self-conscious animals are morally neutral–such as killing, overconsumption of resources, deception–these become moral issues. An early human who kills or excludes a tribe member is committing sin, unlike a baboon who kills or exiles a competing male. A human who eats far more than his share of food in a lean year is committing the sin of greed against his starving tribes people. A human who in a drought year lies about where a water source is commits sin, unlike a bird who engages in deception to ensure the survival of its young.
Thus, evolution into moral consciousness entails evolution into the recognition of sin and the possibility of not sinning, and the recognition that we are all born into this condition, that it is original to our very nature in an incomplete, unfinished universe.
StAnastasia