Well, not just assuming that. It also assumes :That is assuming that life indeed "evolved", or more to the point, that inanimate matter became animate matter and proceeded from there.
The universe is simply too big for intelligence to evolve only on one planet.
Neither can be proven or disproven. And thus, cannot be a logical basis for an argument.
Now the bible, and tradition, is pretty clear that there is intelligent life outside of the human life we have here on earth. But I somehow doubt angels are what is being spoken of in this theory that there is life on another planet somewhere.
To that, we can address two different ways...
We can point out that evolution does not really explain things, as has been done in a previous post.
And we can also point out that an appeal to large numbers does not indicate there is intelligent life elsewhere in this universe.
The more we look into the universe, the more we find variations on how conditions are all wrong for life to exist.
There is nothing to indicate that elsewhere the conditions are just right as they are here on earth.
So, I believe my original submission stands...this is not something the church needs to reconcile until intelligent life on other planets can be proven.