The basic argument of an atheist is "If there is a God then prove it, where is the evidence? I can't see him, I've never seen a miracle, there is no evidence of supernatural powers or beings." Replace those words with aliens and you get the exact same argument. Anyone who argues against the existence of God has to give the exact same arguments against the existence of aliens. I'm in the opposite category, despite my faith I say "There are no aliens in this galaxy, prove me wrong." It's unreasonable to say that even one other intelligent species evolved in our galaxy because that requires wild coincidences about why they aren't here. Some of those coincidences say:
1 They evolved at almost exactly the same time as we did (beating the odds of 13 billion to one)
2 they aren't explorers, they just stayed home, and they never sent out robotic exploration ships
3 they killed themselves (war, suicide, plague) before launching robotic exploration machines
4 they all died because of natural events (asteroids, supernovae, plague) before launching robotic exploration machines
5 their robots came and left before we noticed and left no evidence of their visit, and are probably secretly watching us
6 they have a Prime Directive and they won't visit us until x happens .... and maybe never
Many people confuse the evolution of life with the evolution of intelligent life. They say life evolves easily and that life is everywhere in our galaxy, but they are not talking about intelligent life, they are talking about bacteria. The Rare Earth explanation for the Fermi Paradox is not about planets, it's not about atmospheres, and it's not about bacteria. It's about space faring sentient life. I could not care less if there are bacteria in every stellar system in this galaxy. That is boring and has nothing at all to do with the Fermi Paradox.
The evolution of intelligent life is rare, extremely rare. So rare that the rate per galaxy is well below 1.0 per 13 billion years. If FTL is possible then the Fermi Paradox requires that the rate of evolution of intelligent life is about once in 13 billion years per universe. That means we are alone in the entire universe.
Prove me wrong with evidence, not conjecture. Don't tell me what "we all know to be true" especially all you atheists, because you won't accept that argument for the existence of God.