It would in the sense that for certain fundamentalist groups, there
can be no other worlds in the Universe with life as God/Christ came
to save only us. Jesus does not go planet-hopping (though some
Christian thinkers in centuries past surmised He did just that).

Finding actual ETI would cause a lot of rethinking and probably
strife, but for the diehards, it would not dissolve their faith, nor
should such a discovery create such a result. If anything, people
who think that God or a god made and runs the Universe should
not be so amazed at or try to limit the abilities of such a powerful
being.

Now as for learning more about the Universe and the Concept of
God from an ETI, if we can actually understand each other, our
science-based knowledge of cosmology would almost certainly
get a major boost. But as for religion - would ETI also share a
mystical wonderment of existence in their past development, or
would it be a truly alien concept to them?

And what if they are convinced that their god is THE GOD and
feel it is their holy mission to convert the primitive natives of
Sol 3....