I realize there are arguments, but there are many who find those arguments flawed. To them, for example, multiple manifestations of a single Christ would not be a good answer. Christ died once for our sins. He didn't die multiple times for multiple sentient species.
And the old fallback positions "God's way are mysterious" or "We have more important things to worry about in our own lives" may provide personal solace, but these are laughable to those whom we wish to bring closer to Christ.
Quix had a point.
However the hunch that we are not alone has a classic Christian explanation. Witness needs to deal with questions and objections that the audience states. Not with an infinity of hypotheticals.
And oddly enough popular culture about ET’s tends to bolster the demon thesis. For one thing it seems to have disdain for spirituality as we know it.