I've never been a big fan of Alignment in D&D. First off, I don't agree with the given definitions of "Good" and "Evil". I am a traditionalist when it comes to defining Good and Evil, and hold to the views of Thomas Aquinas. Namely, that Good and Evil are not opposites, any more than Hot and Cold are opposites. In fact, "Cold" is the absence of Heat. Remove all molecular activity, all "heat", and you get Absolute Zero. In such a way, remove all Goodness, and you get absolute Evil. Evil is not a "thing", but the privation of a "thing". Blindness is the privation of sight. Illness is the privation of health. Selfishness is the privation of Generosity.
If this line of reasoning is followed, then "Neutral" as defined in game terms is actually evil. It is essentially defined (apart from Druids) as selfishness. The definitions of Evil in D&D seem more related to sociopaths than anything else.
Of course, my interpretation of Good and Evil won't necessarily match those of my players, so I'm faced with an interesting conundrum. I can either force my views on the system, re-defining the alignments as I see them, or I can "suck it up", and ignore my own views, and just go with the game definitions. As I don't see either of these as an acceptable course, I have to find a third way.
Part of that way is to discard alignment entirely. Rather, expectation for character actions is defined by the game world, and what the people and gods of that game world view as "good" or "evil". Consequence of acting in certain ways is not defined by game rules, but how the world reacts to those actions.
Each of the 7 gods in the game world have their own notion of "Good". For Hydros, god/goddess of the waters, polluting water or slaughtering water creatures is "evil". For Gaia, making the earth infertile is "evil". For Phusis, wantonly destroying vegetation is evil. And for Phanes, disregard for life itself, of animal or man, is evil.
A Cleric as healer is by default given his powers by Phanes, god of all living creatures. The question becomes, why would he be given such powers? My response is that such power is given because the character has shown a special aptitude for valuing life. It is a reward for the Cleric simply being "who he is". An individual who embraces all of creation, and devotes his life to protecting it, may find each of the gods giving him a gift. This is far from being "neutral". It is a calling to restore wholeness where ever possible... to counter the "privation" that is Evil.
A cleric can heal because he is granted the power to heal by Phanes. A Cleric can turn undead because undead are an abomination... a corruption of the creation of Phanes. To the undead, the symbol of Phanes is like a mirror, which forces to see themselves for what they are, and how far they have fallen from form in which they were created.
The Druid shares with the Cleric a reverence for all living things. However, he does not derive his powers from the Gods. Rather, the Druid has learned the language of the tree, and the blade of grass. The language of the wind, and of the stone. The Druid speaks directly to Nature as an ally and companion.
The Druid (and Bard) is not "Neutral" when it comes to man. He has bonds to his clan, and to his people. He is impartial judge in disputes between clans, and judges disputes within the clan. He protects his people from outsiders who would exploit the resources of the clan territory for their own gain. He is seldom an adventurer, unless it is to further his power, or to protect his people. He might be considered "apathetic" to outsiders, people not of the clans, but he seldom acts for his own gain. He certainly never acts to advance the cause of "Evil", unless he has been corrupted. He has no concept of a "balance" between Good and Evil. Courage, Truth, and Wisdom are among the highest "Goods" of the Druid.
Magic Users deal with demonic spirits as a matter of course. They have to be very careful not to abuse their power, and can easily be drawn down dark paths. Anyone suspected of animating the dead would be shunned, if not put on trial, perhaps burned at the stake. Anyone harming someone with magic is likely to be hung. Even simple public displays of magic can cause problems for a magic user, as they are likely to be labeled as a conjurer and trouble maker.
As for fighters and thieves, their actions speak for themselves. A thief might be able to find reputable employment, but for the most part, their abilities, like those of spell casters, are best relegated to actions that are out of sight of the general public.
It is behavior, not "alignment", that is important. People are not evil, but may act in evil ways. Monsters on the other hand, are corruptions of creation, and as such are inherently evil. Their presence, like the undead, will "radiate" evil to those who have the ability to detect it. It is actually their malice and hatred that is detected, so strong it is.