I wish I had a good answer.
Here's what I wrote in reply to the message:
You could say I've side-stepped that question - there are no non-terrans IMTU. Part of that is simply logistics; humans provide enough conflict potential that I don't 'need' aliens. The other part is that whether any beings from elsewhere in the universe bear the Image of God as humans do, is a question I'm hesitant to touch. The Church has no teaching on this; it's simply not been addressed, so I'm leaving it alone. Non-humans in the Body of Christ is, I think, possible, for God can do all things, whatever is pleasing to Him. We know that he formed us in His image; we don't know if He formed anyone else so. My blog and gaming are about how we humans will relate to God in the Far Future, and right now.
Someone might point out that right over here I have a discussion of some 'uplifted' Terran animals as quasi-aliens IMTU. True, although I don't use them much. However, even with intelligence comparable to humans, dogs and dolphins are still creatures about which God did not say "let Us make [them] in Our Image, according to Our likeness" (Genesis 1:26). God "made the wild animals of the earth according to their kind" (Gn. 1:25) but "formed man out of dust from the ground, and breathed in his face the breath of life; and man became a living soul" (Gn 2:7)
That means humans are distinct from other creatures of this world in our nature (our kind). We are Image-bearers, bears are not. (Bears are still awesome) The Body of Christ (the Church) is composed of those who share in His nature - that is, who bear His image.
We know nothing of the nature of any being from another world, it was not necessary at the time of the writing of Genesis for us to know such things. Some day if we find that there are other living beings in the universe, then we will have to discern whether they too bear the Image of God. That day will surely be interesting, if it ever comes.
My friend, if you're reading this, I hope that you do not mind my relating our discussion here. I've left your name out for privacy's sake. If I offend, please forgive me.
Scripture quotations taken from The Orthodox Study Bible
Photo credit: an Orthodox church in Tbilisi, Georgia