From a human perspective, man will not live as God desires him to live unless he is threatened with uncertainty about his eternal destiny.
As popular as this notion is, however, it is false. It reflects a weak view of the power of God’s truth to create a new creature at the moment of saving faith. It also underestimates God’s capacity to transform the saved individual into the likeness of Christ. It hopelessly misjudges the comparative power of fear and gratitude as motivations for right conduct. And beyond all this, it fails to take into account the powerful inspiration of goals that are centered in eternity itself. That is, it neglects the doctrine of rewards.
(From The Gospel Under Siege)