There is sufficient circumstantial evidence for bacterial life on Mars.
The (perhaps religiously) conservative science establishment refuses to conclusively accept it.
When a robotic mission is sent to Mars with the express purpose of finding current life, then it will become obvious that hardened bacteria spores not only survive in our solar system's space, but thrive in the most difficult environments. And what about that stuff growing outside the international space station?
The question about why certain bacteria on earth are very resistant to the sun's harmful radiation is waiting to be solved.
The threat to some of the world's religions is the hypothesis that the simplest life did not originate on this planet first. So what?
Eh, religions have to dispel a dozen graver epistemic threats than that before breakfast every morning. If and when evidence of extraterrestrial life is found, religious people will adapt their beliefs to accommodate it and retcon it, just like they always have.
It's what they've done, very successfully, ever since they had to stop burning heretics at the stake.
>adapt their beliefs to accommodate it and retcon it
I believe this is called “learning” in common nomenclature. They do the same thing in science very regularly, and it’s a pretty obvious part of discovering the world around you.