An interesting disagreement among orthodox Christians, even among orthodox Catholics, is whether the devil should be hated. I have run into a number of people who think in the affirmative. In fact, anecdotal evidence suggests that that is the more common position. On the other hand, I think we should not hate the devil—in fact, we should love him.
Here are some plausibilistic arguments for my position:
- Surely, we should not hate the souls in hell. But if the reason for hating the devil is that he cannot repent of his wickedness, then the same applies to the souls in hell. And if the reason for hating the devil is his evil works and his empty promises, then that's a bad reason—it's a reason for hating the evil works and the empty promises, but not for hating the devil.
- Anything that is good deserves to be loved to the extent that it is good. Anything that exists is good to the extent that it exists. Thus, the devil deserves to be loved to the extent that he exists. And to the extent that he does not exist, surely then it is not he, who exists, who is to be hated, but the fact that he does not exist fully should be hated. (Yes, one can hate its being the case that p.)
- Love and hatred are closely tied to actions. Now the actions we should engage in with respect to the devil are ones that are good for him, and hence they are more like loving than like hateful actions. For instance, we should reject the devil's temptations. That is good, because by rejecting the temptations we make him be responsible for fewer evils than he would be responsible for if we yielded, and it is bad for one to be responsible for evils. We should shun the devil's company. But to be in the devil's company, we would have to be wicked. And it harms a person to be provided with wicked companions. Furthermore, we should strive to frustrate the devil's wicked plans. While the frustration of one's plans may be bad for one in one way, in a more salient way, it is good for one when the plans are wicked. It is a bad thing for one to succeed at evil.
On the other hand, one might worry that love has a unitive dimension, and then one might argue that we should, surely, not seek to be united to the devil—that is just too dangerous. However, we can be united simply by doing good to someone, and there are ways of doing good to the devil that do not carry undue danger—for instance, we can, as noted above, do good to the devil by frustrating his evil designs. Another good we could do to the devil, should God assign this to us (we are mysteriously told that we'll judge angels), could be to condemn him to punishment, if it is intrinsically good to be punished for one's wickedness.
At the same time, the love should not have much intensity. The devil is dangerous, and we should not think too much about him. Maybe I have already done too much.