We do not die physically because of anything Adam did. Adam died spiritually when he sinned, when he disobeyed God. He died physically because that was how he was created. He was not created immortal; rather he was created with a mortal physical body. So long as he obeyed, he was allowed to stay in the Garden wherein there was the Tree of Life which guarded against his physical dying. When he sinned, God ejected him from the garden and he no longer had access to the fruit of the Tree of Life. The result of that was that he eventually died the physical death which was an integral feature of the entire creation. Nothing about this creation was to last forever.
In Adam, meaning being a human being, all die physically. The wages of sin is (spiritual) death. Babies die because they are human.
That's one way of looking at it.
However, Adam and Eve were made perfect. The Garden was perfect, trees, plants and even animals were perfect (aside from the fact that evil was lurking: Satan was allowed in there to tempt them and the potential for evil > the Tree of Knowledge of Good and EVIL). It can't think that the presense of Satan and the potential of evil in the Garden was a perfect set up. No, because it wasn't intended to last. Likely they sinned within nine months of creation. Why do I say that? Because Eve was hot and it wouldn't take long before Adam figured out what sex was.
So the question is, with a perfect body and perfect food and without evil not released yet, what could physically cause them to die?
Realize that death is a process of cells dying daily, organs and systems within breaking down, growing old and eventually no longer functioning.
This process started when sin came into the world and into their bodies.
Sin distorted creation down to the cellular level. Cells began to mutate and die that eventually had effects on their lives ... they started to age and o casionaly get sick. Plants and animals suffered the same distortions. Animals became fearful of man and now evil influenced their behavior. What was harmonious in the Garden, turned to discord. Animals, passive and friendly, immediately turned into predictors or prey and some very dangerous. The eco-system was physically infected with this harmful/distortion and defects began to emerge. Harmful bacteria and viruses began on that day to develop. Still, their bodies were well made and so they endured for 1000 years, but over many generations, we see that these mutations accumulated and became deadly.
So the wages of sin is both physical and spiritual death. You might ask, But what about the Tree of Life, they could 't have lived forever unless they ate of it? True.
But this was God's plan all along,
that we would know good and evil, and appreciate what good is and know Him. Think about it, we could not know what the meaning of mercy, forgiveness, healing, love, faith, kindness, joy, patience or peace unless we experience their opposites. When we experience pain and suffering, or despair, hate, hunger and death, then when good comes along, we really appreciate it, we really begin to understand what good is, who God is and all of His attributes.
