The Athiest Myth

I'm always intrigued when outspoken atheists claim that the world will be a better place once we eliminate the irrationality that is religion. I've ranted on this topic at great length elsewhere, but I'll sum up my ideas here.

a. Yes, atheists are good people that care for others and don't (always) look down on the foolish theists. aka: atheists are not evil people
b. Yes, many of the greatest atrocities in the world have been done in the name of a particular religion or God.
c. Yes, there have been no great atrocities in the name of atheism. They were committed in the name of social, political, or economic causes that happened to be atheistic. (correlation does not equal causation)

Unfortunately, this does not mean that the world will be better off with just atheism. That is because atheism lacks a central belief to claim what "good" is. Why is that?

1. There can be no objective good in an atheistic world-view. The human animal may live or die just like any animal. The species can thrive or perish at no harm to the universe or reality. Nature does not have a happy harmony, just a struggle against/with others to survive. Obviously, this should be my most controversial point that the others build upon.
2. "Good" becomes defined as a social construct. What ever most people agree is good or is forced upon them as by those in power will be defined as good. This would be seen at the most animalistic level as survival of the genetic material of the individual. At the highest level, this would be a peaceful, harmonious society where everyone prospers and no one suffers. But not necessarily.
3. There would be a competition amongst people to have their version of "good" be victorious. Anarchists, facists, capitalists, and hippies all have their own version of "good" and an ideal perfect world. This is not claiming there would be bloodshed, only that there is no central concept of what good is.
4. Evil could even be defined as "good," and a true atheistic rationalist cannot argue against it. All of the authoritarian futures such as 1984, Matrix, and Brave New World are acceptable because the society allows it (to the consternation of a few individuals). There is no greater understanding of morality to which a rationalist can appeal.

• Genetic material passed on - check. Though why humans have to survive, I'm not sure (see #1).
• Social consesus - check.

What am I missing? Why would the planet be better off without religion when "better off" implies a value judgement I don't think atheists can make? Why is peace a good thing in an atheistic world-view? What makes the survival of the human species, or even an individual human a desirable thing?