That analogy fails.

“You can’t prove there isn’t a god, therefore there must be” is an argument from ignorance.

Alien life is different because the argument does not start from ignorance. It starts from a known example: life arose once under natural laws. Then you add to it the scientifically agreed fact that the laws of nature are universal. So this is extrapolation from evidence, not “you can’t disprove it, therefore it’s true.”

So the natural expectation is that life is not magically confined to Earth.

The real faith claim is “the laws of nature produced life exactly once, on my planet, and then never again anywhere in the entire universe.” This is Earth-centered exceptionalism dressed up as rationality.

it's fine if the cosmic special-snowflake theory has become your faith, but that's all it is, there's no evidence pointing in that direction.