Genesis 2:17

but of the tree of the knowledge of good and evil, thou shalt not eat of it; for in the day that thou eatest thereof thou shalt surely die. This was a very general permission or command: of every tree of the garden eating thou shalt eat. There were fruit-trees of every kind in the park, and their fruit was at the disposal of man, even the tree of life with the fruit which was intended to sustain him until the Lord was ready to make his body spiritual and to take him up to heaven. But the prohibition was absolute with regard to the tree of knowledge in the midst of the garden. This tree was placed there for the exercise of man's obedience toward God, and the transgression of God's command would result in man's becoming mortal, becoming subject to death. From the day that he would eat of this forbidden fruit, the germ of death would enter his body, and his final dissolution would be inevitable. If man had stood this test, he would have been confirmed in his possession of Paradise, and through his eating of the tree of life he would finally have been enabled, without pain and death, to enter into the life of eternity. Death is the consequence of disobedience, of sin.