I'm not sure I'd go that far into cultural relativism. The "habitual practice" of the Third Reich was to gas Jews and the habitual practice of Americans in the antebellum South was to own slaves. Regardless of what people in those societies felt about it, I think it was morally wrong then and now. The habitual practice among fundamentalist Christians is biblical literalism, which I think is a perversion of morality. Just as we can say that the atrocities committed by Israelites allegedly under God's direction were wrong, we can say that the atrocities committed by the Bush administration were wrong, regardless of how many Americans were habitually conditioned to accept them.
We can say just about anything it seems which is why I look at this question from the standpoint of definition. The definitions suggest that there is no universal morality beyond me and mine. However the definitions suggest also that the op is mistaken in his premise.
Defining key terms is half the battle, but I think the definition you provided fails adequately to distinguish between morality and custom. Here are a couple I prefer: moral quality or character; rightness or wrongness, as of an action the character of being in accord with the principles or standards of right conduct; right conduct; sometimes, specif., virtue in sexual conduct principles of right and wrong in conduct; ethics a particular system of such principles moral instruction or a moral lesson a narrative with a moral lesson. Webster's New World College Dictionary, Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio. mo·ral·i·ty 1. The quality of being in accord with standards of right or good conduct. 2. A system of ideas of right and wrong conduct: religious morality; Christian morality. 3. Virtuous conduct. 4. A rule or lesson in moral conduct. The American Heritage® Dictionary of the English Language, Fourth Edition copyright ©2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved. I think I'll go to bat for the op on this one. I think that religion can help to enhance and define morality, but it's possible for non-religious or at least non-theistic people to have a refined moral sense. I think morality is rooted in empathy for others, the agapic principle, and the "categorical imperative". These are all principles taught and exemplified (but not exclusively) by Jesus. Empathy, of course, is the ability to feel another's pain and to put ourselves in his/her shoes. The agapic principle is unconditional love that permeates the teachings and example of Jesus, but others could follow, as well. The categorical imperative is Kant's concept that we should universalize the maxims that we follow--similar to the Golden Rule, "do unto others..." The bigger problem is motivating people to abide by these principles, but that's a problem whether the people are atheist, Christian, or whatever. Fear of divine punishment doesn't seem to be foolproof, by any means, in getting people to behave.
The definitions I have put forth remove the specter of arbitrariness contained in the considerations of "right and wrong" I do not lean to definitions, I prefer. The definitions I put forth allow for every conjugation of the words and by definition demonstrate that god or an idea of good is necessary to have a morality greater than the instinct for self preservation. Religion and god are two distinct phenomena. The definition of god I put forth is, that which is invoked. I did not consider religion in my definitions. It is necessary to have a model of good in order to have a refined moral sense because that is what a refined moral sense is. I think morality is rooted in the recognition of real nature. To me love is without condition and is therefore beyond what can be taught, therefore speaking of the agapic principle, the principle of "brotherly love", is not really meaningful in describing conditions. We are devoted to the maintenance of our physical estate. To love your brother as your self then is to watch his back as though your own life depended upon it, which in fact it does. A reflection of our true and demonstrable relationship to each other. In this world we exist with and for, each other. Our behavior flows naturally from our model of good or "beliefs about the world". Behavior does not respect manipulation.
Morality is not complicated at all. It is a simple empathetic behavior processing right and wrong and having the fortitude to act accordingly. The problem is when you add organized ignorance, then morality is only a self gratifying illusion. I'm sure Islamic extremists 'believe' that stoning a girl to death as punishment for being raped is a morally just punishment. But really we KNOW they are FUCKED in the head!
I'm not sure I understand all that, but I think it comes down mainly to semantics. I sense that what you're saying is that all morality must be rooted in a concept of ultimate good, and that ultimate good is called God. If that's what you're saying, I can agree with it. It's basically like Tillich's Ground of Being. I think there's something to be said for Relaxx's idea that "it's a simple empathetic behavior processing right and wrong and having the fortitude to act accordingly". But I don't think "right and wrong" are nearly as simple and straightforward as he suggests. There are lots of cultural influences that shape our sense of right and wrong, religion being only one of them. In 1964, when Goldwater was running on the Republican ticket, the Republicans put out a campaign add "In your heart, you know he's right." But LBJ won by a landslide. In my heart, I know the Republicans are wrong--morally. But there's a (remote) possibility that I'm wrong. Note: these are not religious dictates; but they are about right and wrong. Secular ideologies can mess up people's heads as badly as religions, Ayn Rand's atheistic objectivism and atheistic Marxism-lenninism being classic examples. And plenty of people can be morally messed up without an ideology. But I agree with Relaxx that empathy is the key.