Well, isn't the point of moral relativity that it
isn't consistent?
Not all kinds of charity is good, to use your example. Donating clothes to people in underdeveloped countries may seem like a good thing to do, but in actuality the over abundance of clothing puts local clothes-makers (sewers, tailors, fabric makers, sheep farmers, etc.) out of business, decreasing jobs and increasing poverty. Giving food to the Red-Cross in the form of canned goods or boxed meals may seem generous, but since each item must be sorted and examined separately by hand to make sure it is undamaged and pre-expiration date, the extra manpower needed to process it actually costs the organization more money than the food is worth.
Now, murder is an English word that means 'unlawful/wrongful killing' (depending on the dictionary) so it is wrong by definition. 'Wrong thing is wrong' is obviously always going to be true. But, what one culture or person considers a wrongful killing, another may believe to be perfectly justified. Perhaps if someone did something terrible to you or your family (and I sincerely hope no one does) you would feel like hurting or killing them would not be a wrong thing to do. The law--and other people--may disagree.
So, what is right or what is wrong depends not only on the circumstances (an action may cause harm in one case and good in another) but also the perspective of the person forming the opinion. When perspectives under certain circumstances are similar throughout the population, it is made into law.
It's messy, it's complicated, it's full of gray areas and disagreements and changing social patterns and all kinds of weirdness. The people who think there is such a thing as objective morality are looking for the easy way out. They imagine one set of cosmic perfect rules (usually the ones they grew up with, fancy that) and then let that excuse them from thinking too hard or examining their own beliefs with the scrutiny they deserve.
What we need to remember is that many of the things we think are alright today were once considered very, very wrong, and many of the things we think are very wrong were once considered perfectly normal. Would you, as a young woman about to enter adulthood, like to have been married off to a forty-year-old man you never met before at the age of twelve and have two or three kids by now?
No?
Me neither. Today we consider that pedophilia and child abuse. Our many-greats-ancestors called it traditional family values.
We are an evolving species, not just physically, but also socially. Look at how much better we treat each other now than we did just a few centuries ago. Imagine how much better our children's children will be treated.
Gosh, what's the point of anything if you don't get to live forever? [/sarcasm]
You have to find--or create--your own meaning in life, and in my opinion, the farther you can do it from religion, the better. As an atheist, I think one of the greatest tragedies is the vast numbers of people who spent their only short time on this planet suffering or toiling or fighting for the hope of something better afterwards, only to receive nothing. There is a reason the slave-owners of the South taught their slaves to adhere to their master's religion--what better tool for keeping an uneducated population in check, than instilling a belief that blind obedience is good, suffering is noble, and reward is guaranteed only after you no longer live and therefore can't complain if it isn't there?
Now, suffering, toiling, or fighting to make THIS world better for you and for your children, I can understand that. Which gets back to survival of the fittest, in a round-a-bout way. Systems of morals and beliefs are also subject to evolution. Tiny changes in accepted thought creates societies better capable of working together and surviving in the world.
Why does it matter, you ask, if we're all going to die and the universe is going to ka-boom in a million trillion years or whatever? Well in the long run you're right, it doesn't matter at all to the universe because the universe wouldn't care if we blew ourselves to tiny bits.
But here, and now, and to us, it matters. We make it matter.