I think I know where you're going with this thread. Here's why it's fallacious. The possibility of extraterrestrial life is helped along by that fact that we know of possible mechanisms by which it could have arisen(those being the same or roughly the same as the ones by which life on Earth may have arisen). http://en.m.wikipedia.org/wiki/Abiogenesis (go to current model) Then there's our knowledge of stellar evolution and planetary formation which suggests, along with the sheer ridiculous number of exo planets we've found, that planets outnumber the stars in our Universe. Due to the huge numbers involved, planets with favorable conditions for life as we know it are a statistical inevitability(let's not forget the possibility of life not as we know it). If chemistry acts the same across our universe(as the Copernican principle says it should) then extraterrestrial life is rendered statistically likely. Far from a faith based claim.