Well I don't claim to know everything, but personally I'm inclined to believe that we are the only beings in the known universe created by God.
In the Weekly Survey thread I put the question do you believe in aliens in my first survey and in my own answer I said that according to one Christian book I've read aliens are nothing more than the forces of evil impersonating as beings from other planets in order to turn people's attention away from their loving creator God.
But to each his or her own, I don't want to argue. I only wished to state my honest opinion.