1. Who are the scientists that declare there must be millions of alien civilizations in the universe?
Carl Sagan said it while alive. Even sent a time capsule. SETI scientists.
2. How do you know they are atheists?
God didn't create aliens, so aliens would be evidence against God.
3. You would need to define god before showing proof of god. There often seems to be some disagreement about what constitutes god.
No aliens = evidence for God.
4. You should probably be saying evidence rather than proof. You believe the Bible is evidence of god. I'm not sure what the statement "a Bible that somehow came to be" means; it came to be when it was written? You seem to imply that it couldn't have been written but had to be created by god.
Don't be so dumb as to be influenced by Satan. It's God. god is considered Satan aka god of the world in the Bible.
5. That places written about in the Bible exist seems like pretty scant evidence of god. Places written in most Stephen King books exist, but that doesn't mean I should start believing in monsters.
You're entitled to your worldview even though it's wrong, wrong, wrong.
6. Why would you assume that if aliens existed, they would have contacted us? The universe is
vast, almost beyond human comprehension. There could be tons of alien civilizations out there without they or us ever noticing each other. Besides, it's also possible aliens have attempted to contact us and we did not realize it. It isn't as if aliens are likely to be sending messages out in human language over devices compatible with human technology.
This is ignorant. NASA, SETI, Elon Musk all think we have been contacted even thought there is no evidence. Read about the Ferdi Paradox.