The Self-interest Theory has long been dominant. It has been assumed for more than two millennia, that it is irrational for anyone to do what he knows will be worse for himself. Christians have assumed this since, if Christianity is true, morality and self-interest coincide. If wrongdoers know that they will go to Hell, each will know that, in acting wrongly, he is doing what will be worse for himself.
Derek Parfit (1984:130) Reasons and Persons OUP