Do I believe we're the only life in the universe? No, I don't. I view such an assumption to demonstrate the most profound amount of arrogance and self-conceit that one could imagine in the universe. But how would the emergence of other intelligent life impact Christians? The degree of opinion varies widely among those who identify as Christians. The viewpoints vary from "intelligent life doesn't exist." to "The UFO's are demons" to "I don't care, doesn't matter to me." to "I don't know." And I would say that the "I Don't Know" question is actually probably the most fair response I've heard on this particular question. But here's the great thing about the Red Letters of the New Testament. It applies to anything, anyone, any circumstance, ANYTHING...it doesn't matter who, what, or where you are from. So, let me pain this scenario:
We discover intelligent life, that life joins us on Earth, visiting sporadically like that of an international tourist. Do we welcome them with open arms, do we embrace them as fellow intelligent lifers of the Universe? Do we share with them the values of our varying societies? Yes, we do.
As Christians, we are obligated to love our neighbor. As the Group, The Christian Left put it on a T-shirt so eloquently, Love Thy...(Insert identifying characteristic). I think Love Thy Interplanetary Person would definitely fit alongside Love thy Gay Neighbor, Thy Immigrant Neighbor, and Thy Addicted Neighbor...and so forth. As Gentiles, persons not born of the line of David or the Nation of Israel, we were given the right to join in the Promise of Abraham as adopted brothers and sisters. And guess what? So would any extraterrestrial intelligent life.
I know we're probably way off for this particular issue to be addressed, but, might as well address it now :).
Our chief mission and most important tenant in this life.