Holy sweet IPU's tits on a popsicle stick. You don't like religion, therefore you want to leave the planet?
Seriously?
I see this on a smaller scale all the time. People leave to another city thinking it will solve all of their problems, only to find the same problems in the new city. Why? Because the problem wasn't the old city, they were creating their own problems. You're proposing more or less the same thing here, but on a much more expensive and wasteful scale.
Religion isn't the fucking problem. We are.
Religion is a symptom, not the disease. The real problem is sloppy thinking. Religion isn't the source of our sloppy thinking, it's the product of our sloppy thinking. Plenty of research in neuroscience shows that we're all sloppy thinkers most of the time; the best of us just get a few more moments of clarity than the others. Even when we think we're being cold and calculating, we're mostly just making snap decisions based on instinct, emotion, and a terrifyingly large list of cognitive biases:
http://en.wikipedia.org/wiki/List_of_cognitive_biases
Even if you gathered up all the atheists, put us on a spaceship, and moved us to another planet, you would still end up with most of the same problems. There might be differences in some of the details, but you'd still have most of the same crap going on. How can I make such a prediction with such confidence? Because we already watched more or less the same thing happen with the Soviet Union.
Religion was almost entirely out of the picture as an influence on the government, and yet as Hitchens pointed out, they turned an economic philosophy into a religion, then proceeded to commit all the same crimes we associate with organized religion including proselytizing and punishing people (sometimes severely) for blasphemy. They had priests and preachers and missionaries and even goddamned prophets. Communism-as-religion had exactly the same ties to the government that many religions once did (and in some places still do). Fuck, at one point they even forbade scientists to work from the assumption that evolution is true.
To me this proves that religion isn't the problem. Human beings are the problem.
We are the problem.
How about before running away to another planet, you try to address the real problem: figuring out how to better teach critical thinking to our children? Solve that problem, and your atheist space colony will actually be viable. But then, if you solve that problem, there's no reason to leave the planet, is there?