Human survival + religion
In the series they assume that the human race will outlive the earth. This is a remarkable vote of confidence in our race, which I personally share. I really believe science will prevail one day instead of a couple of vague religions based on a few books which in my opinion are no more than travelreports and 'novels' from the past. (Yes I am talking about the Bible and the Koran).
Maybe when people in general start thinking a little more scientific or simply open their minds they wouldn't fight over 'which book is right' and start looking further than these religions which do no more than comfort people in their existence and blind them from the rest of the world (and the universe for that matter).
Jesus Christ was no more than a good man who loved humanity. Why christianity went completely over the top? I don't know. If you want to believe in something, believe in yourself and believe in the human race. Not someone who died approximately 2000 years ago or something called God which is merely a name for something we can't understand (yet). Science will one day figure out how we got here and what life means.
I have faith in the human race, I don't think we will destroy ourselves.
But ofcourse, it is your life, do with it what you want!