One poster raised the issue of a deity that is harsh / 'evil' towards outsiders but helpful / 'good' towards their own people.
What we have to remember is that in pre-modern times many peoples did not necessarily view outsiders as people. Many tribes - whether in the Americas, Africa, Australia, or Asia - often had a name for themselves that translated as 'people. Outsiders could become 'people', but they were not to be considered 'people' - or given the rights / respects / consideration of such - until some form of adoption process had occurred (usually a variant of their coming of age ceremony, although marriage into the tribe also worked, usually).
So the viking raiders - known to much of Europe for their savagery, deceit, cruelty, pillaging, and generally dishonorable behavior - were, in their homelands, just as well known for their generosity, truthfulness, honor, and so forth. They did not have a split personality. Those in their homelands were 'people' and were treated as such. Those outside their homelands were less than those in their homelands - although I'll admit I do not know offhand whether they considered them non-people.
Similarly, there are tribes in Africa, central Asia, and elsewhere that are known for harshness towards non-people (ie: outsiders) but honor and such towards people (ie: their tribal members). Even Europe during the 1500s - 1600s was not quite exempt. There was a famous instance where the Pope was questioned as to whether the native americans had souls and thus should not be enslaved, etc. He replied they did, but the fact that the question even was asked in the first place shows that the idea existed of a division between humans who are 'people' and should be treated as such and humans that are 'non-people' and not worthy of respect, etc.
Many ancient religions tended to have deities who were gloried for their harshness towards non-members of the tribe and benevolence towards members of the tribe that worshipped them. Thus many deities were viewed as fiendish or at least uncaring from the perspective of outsiders and benevolent / honorable from the perspective of insiders.
Considering the whole of the human race 'people' is more of a modern than ancient concept - or at least it is far more common now than then.
So, I tend to ignore alignment entirely in dealing with fantasy deities. If they are based on ancient / historical patterns, then they are likely both viewed as good and act as good towards their own worshipers and either utterly indifferent or callously cruel towards non-followers. I'm not sure if any setting - either game or novel - currently on the market accurately depicts such a situation (in part because it is not politically correct to have such a discriminatory view), but it would help make sense of the various 'evil' deities in a campaign setting. After all, very few deities in the ancient world were typically viewed as 'evil'. They were maliciously mischievious or indifferently uncaring, but very rarely were they seen as 'evil' by their followers. Even Loki was known for a few acts of random kindness, for example.
Those that were viewed as maliciously mischievious or indifferently callous were worshiped more to placate them - either beforehand or after the fact if problems developed later and an augury pointed out the unknown sin that lead to the problems being sent against the community. The norse deity of the deeper sea (forget his name at the moment), was given sacrifice before major sea voyages not to show love of a deity, nor even to show fear of a deity, but rather to show respect, in the hope that the deity - should he consider sending a storm, might decide otherwise. Or, if he takes any notice of them while they are sailing upon his domain, he might take offense upon realizing that they did not show him respect before 'trespassing'. Even if you do not agree with a person or their views, if they have the means of killing you at any instant upon a whim, you should likely respect their power and not seek to purposefully antagonize them.
That was generally the view on following proper procedures, giving due respect / sacrifices, etc towards many of the so-called 'evil' deities. You followed the customary luck ritual / traditional sacrifice / ceremonial sign of respect when about to do something they might take notice of (such as entering their domain), so that should they take notice they would realize you had shown respect and not smite you out of irritation from your callous disregard of them and their power over you (by not following the rituals that showed you respected them). In effect, showing such hubris to ignore respecting your (divine) betters.
Those deities that were openly considered evil by their followers were as often associated with or considered fiends (or the cultural equivalent) than true deities. Consider, for instance, that most of the 'evil' greater beings of norse mythology were not deities but instead giants. Surtr, a fire giant, was not a deity and was not worshiped, but in their mythos he was a being of great cruelty and terror, who would one day aid in the destruction of the world.
Yet another example, the Egyptian deity Set - whose name can be translated as either 'one who dazzles' or 'pillar of stability' - was in many ways the equivalent of Shiva, a destroyer deity who, through destruction, aided and kept in place the harmony of the universe. Indeed, he was considered the hero of Ra, ever fighting the terrible demon Apep (the only being in egyptian mythos actually considered evil) so as to prevent evil from overcoming the world. Later conquerers demonized Set in part due to the fact that Set was a rallying point for those loyal to prior pharohs, as he was symbolic of the strength of the throne. But then most deities considered 'evil' were often the result of later demonization by conquering peoples (or those that outlasted the disliked worshipers for any reason, really).
And now I've gone rather far afield from my intended point, so to prevent this from going even more off tangent I will end this here.
