No one in religion has "faith" that "there is a high probability that God exists".<quoted text>Faith; Belief without need of certain proof.
They have "faith" that "God _DOES_ exist".
It does not require faith to conclude that, given what we already know, it is highly likely that SOMEWHERE in the Universe there exists life.
There is no unique component of life found only on Earth. Life is not made up of some element not found on the periodic table.
We've found both the precursors and the byproducts of life elsewhere.
And, the Cosmological Principle holds for life as it does for anything else in the Universe.
Can we prove CONCLUSIVELY that life exists elsewhere? No.
How much of the Universe have we searched? 0.00%
We haven't even found ALL the life which exists on Earth.