As we know, the lie was believed, the penalty for sin denied, and sin entered the world. But even though the authority of the Creator was disputed and ignored, that authority remained, and He acted in His holy justice. For since by man came death, by Man came also the resurrection of the dead. If Adam's sin did not bring physical death, Christ's resurrection from physical death does not bring eternal life. It is obvious then, that death is very important to the Christian world view.
Death is the result of the entrance of sin into the world.
Thus we can see that God was not only acting in His justice in pronouncing the curse of death for sin, but in His grace, as well. For, by establishing the penalty for sin to be death, He made it possible for Him to send His beloved Son to come and die to pay the ultimate penalty for sin as a substitute. Only the holy Creator, the righteous Judge, could be the sinless Substitute. But if death is not the penalty for sin, then the death of Jesus Christ did not pay that penalty, nor did His resurrection from the dead provide eternal life. These ideas destroy the foundation for the Gospel and negate the work of Christ on the cross.