Why are atheists hostile to a belief in a Creator?

[Angrboda]

I can understand the hostility to religious people who get in your face and tell you to turn or burn. Those people drive me nuts. In my case I'm not offering any salvation or condemnation. I'm not preaching to anyone, I'm not quoting scripture. I haven't been involved in any organized religion in close to 20 years. All I'm doing is defending why I claim the universe was intentionally caused to exist by a Creator. I have pointed to known facts which support my claim. Interesting I get virtually no responses detailing the facts and reasons why atheists believe the universe and life came about without the aid of a Creator. Mostly they defend their claim by relentlessly bashing any theist ideas. It always sounds so personal. Often animus and rancor is involved. I tend to throw it back. 

Isn't it true that neither theists or atheists know for a fact what they think is true, is true? Isn't it a bit goofy to be getting our hackles up over an issue both sides concede is unknown? Is it plausible the universe came about unwittingly like all the natural things we see around us? Sure. Is it ironclad fool proof that happened? No because no one actually knows how the universe came into existence. No one knows what it takes to cause a universe or exactly what it takes to cause life. 
 
I don't declare its a fact our existence was intentionally caused. I certainly could be wrong. Its an opinion not based on faith, but on the known facts. It could be true we live in a multiverse and if some direct confirmation comes forth, I would have to tip my hat to those who claimed as much. It would explain the most puzzling fact we know about the universe. That it takes a lot of just so properties, conditions just for stars, solar systems, planets and galaxies to obtain. It seems most atheists I run into don't care for multiverse theory despite the impressive number of reputable scientists who often talk about it as a matter of fact. I'm guessing two reasons. One, they don't concede (or don't want to concede) that the universe is on the absolute razors edge of being life friendly. Not just life friendly but having stars, galaxies and planets. They don't want to believe in something minus direct evidence. 

Likewise few atheists give the simulation hypothesis much attention after all it too would involve intelligent design. I'm not onboard either but I can't flat out reject it. Our own simulations get closer to mimicking reality that they can't be distinguished from reality. With the exponential power in computing in another 50-100 years scientists will probably be able to create virtual people who aren't aware they are virtual and live in a virtual habitat. Amusingly enough those virtual people will no doubt question if there existence was intentionally caused or was unintentionally caused by 'natural forces'. If that happens would atheists concede that reality was intentionally caused to exist?

Do you assert claims that you feel that you are not justified in believing?