Absolutely, it’s a hard thing to figure out. Scientists have been working their whole lives to figure that out. My point is just that hard ≠ impossible.

For example, did the first cell form here on earth, or was it carried here by an asteroid? How would you rule either of these out?

How would I? No clue. But I agree that there is still debate whether panspermia brought life (or the components for life) or whether some other chain of events led to life originating here. I’ve heard cases for both, and I don’t think there’s enough evidence to conclude which it was. Maybe it’s some third option that people disregarded; maybe it will be the definitive proof that theists have been searching for.

Perhaps one day we’ll have a better idea. I’m okay living in the uncertainty in the meantime.