I am also an "a-alienist". I don't believe in aliens. But some scientists over there at the "Search for Extraterrestrial Intelligence" (SETI) in California believe there are good reasons to believe intelligent life exists out there. Now I don't say that I know for sure that there are no aliens. Only that I see no evidence or any convincing reasons to believe that they do exist. Yes I know how huge the universe is and that "surely somewhere else evolution could have happened as well". The thing is I am simply not convinced by these arguments. Show me the evidence I say!
If one is an atheist this is pretty much how the argument goes...
There really are NO good arguments against theism. Therefor atheists changed the definition for "atheism" from a believe that God does not exist to absence of believe in God. Therefore shifting the burden of proof to the theist. Show us the evidence! Say the atheist.
Only difference is, it is very easy to be neutral about the existence of aliens. Their existence or not would not make any difference to my lifestyle! Little bit more difficult to be objective about God though. If you're wrong the consequences could be literally unimaginable... To be objective when your lifestyle demand x and you are confronted with y is not an easy task for the thinking atheist. Actually it is close to impossible.
Just take the ET question again. Say a SETI scientist tells me that it is a top secret but there is actually a constant signal being picked up by them. The existence of ET life would make no difference in my lifestyle and it would be easy to see myself come around to the scientists viewpoint with such evidence. Wow - there is a signal! There must be intelligence out there!
But it is so much more difficult to say: Wow. The universe (or multiverse) began to exist! There must be a cause! [1] Wow. There is something rather than nothing! There must be a creator out there! Wow. Scientists discover the universe was fine tuned for life! The creator seemed to want to create life! [2]. Wow. Objective moral values exist! A morally perfect creator seems to be the best explanation for this.
So. Did an extremely powerful un-embodied (spiritual) moral being create everything and then place moral values on mankind's heart?! [3]
If so. Then he would have surely revealed himself to mankind? We should investigate the religions of the world! Which religion follows a moral being? Not Islam - the Koran says Allah hates the unbeliever. Which religion is set on a historic foundation and cannot be disregarded as mere myths and legends. Not Hinduism - the story about Krishna is clearly legendary and myth (just spend five minutes on Wikipedia).
The remaining world religion is Christianity. Why were people willing to die for the believe that God walked on the earth and revealed himself to mankind through the man Jesus of Nazareth? Let me read the bible to see what this person said!
Alas....
Such sincere enquiry cannot even be considered by some. Why. Because we know it might bring us to a choice. A lifestyle choice that is for some just too much to be confronted with. More evidence is required before some would bring them-self to really take such a sincere step. More evidence would always be required...
Yet for others such a step is such an amazing eye opener they cannot help to delve deeper and to share with all the world. Like the atheist Frenchman from Paris who set out to find a proof to convince his girlfriend that Christianity is false. This search ended up leading him to Christ and (amazingly) to recently become a young Christian theologian after studying in New York. Christianity has a sophistication and ring of truth unparalleled by the other world religions.
Read about his amazing journey at http://www.reasonablefaith.org/how-a-french-atheist-became-a-christian-theologian
[1] The cosmological argument: https://m.youtube.com/watch?v=6CulBuMCLg0[2] The fine tuning of the universe: https://m.youtube.com/watch?v=UpIiIaC4kRA [3] The moral argument: https://m.youtube.com/watch?v=OxiAikEk2vU