To postpone the death, and to make it so that God did not have to be totally separated from Adam, the Father told him that He would require a life - a blood sacrifice. So Adam sacrificed an animal. Anyone who had a relationship with God during this period, and for centuries afterwards, was required to give sacrifices. The sacrifice of an animal was the only atonement for sin that was possible in order to have a relationship with God. Sin is a powerful force that leads to death.
Sin holds, grips, moves, crushes, and destroys.
It never lessens, but always expands and penetrates. It moves from person to person, nation to nation. Sin is silent, we give it voice. The outcome of sin is death. Only death can equal death.