But the criteria aren't the same. You just have to look at the statistics to realise that there is a strong probability of extra-terrestrial (microbial) life existing. It's not "proof" obviously, but it is strong enough that it can be used as the basis for belief. The concept of God doesn't have the same statistical support. People commonly cite the "fine tuning" of the universe but this is a stupid argument for several reasons.
Intelligent alien life is another matter. It's cool to think it could be out there, but I really don't know. Your comparison to God is much more valid when applied to the specific case of intelligent life. I guess my beliefs could be summarised:
1) microbial alien life: yes, definitely. probably widespread on thousands of planets in our galaxy alone.
2) intelligent alien life: maybe, but if it does exist it's VERY rare and seperated from us not just by huge spatial distances but likely by huge temporal ones too. for this reason I doubt we'll ever meet them, therefore agnosticism on the issue is currently the most logical position.
EDIT: regarding microbial alien life. If we find microbes on titan or europa that would indicate that the universe is pretty much teeming with life and would be AMAZING.
Jeez....READ THE THREAD. It is about the possibility...NOT THE PROBABILITY. I have explained this upteen times..


