It is easy to suppose that it is only modern people in Western (or other developed) countries, with the benefit of a scientific education, that grasp the immensity of the universe. After all, it is only relatively recent science that has acquainted us with light years and so forth, and been able to estimate that the light from Andromeda that we saw from Ifaty the other night left that galaxy long before our species even existed.
On the other hand, that self-same science yields the electric lighting and the consequent light pollution that is precisely what prevents modern Western people from having personal daily -- or rather nightly -- direct eye-witness experience of the immensity of things. The Hebrew prophet Isaiah commented that "God that sits above the circle of the Earth, and its inhabitants are like grasshoppers. God stretches out the heavens like a curtain, and spreads them out like a tent to dwell in." Isaiah's cosmology is extremely quaint. Yet this quotation suggests to me that Isaiah may have had a greater visceral sense of human tinyness than most modern Westerners.
What does the immensity of the universe mean for humanity's place in the scheme of things? Given what we now know, can a religious answer to that question be anything other than wildly implausible?
In particular, is not Christianity beyond preposterous? Christianity declares not merely that God exists, and that God cares about us not just as a species on our modest planet but also as individuals, but also even that God became incarnate as one of us. Does that not take human exceptionalism to absurd lengths?
To cap it all, the alleged incarnation is a one-of-a-kind historical event of a miraculous nature. The 18th century Scottish philosopher David Hume (nicknamed by his contemporaries 'The Great Infidel') claimed that a miracle is always more improbable than that those reporting the event are deluded or fraudulent. It seems to me that Hume was begging the question; unless we know the nature of God's intentions, we cannot estimate the probability of what God might do in an exceptional case. But even so, given human tinyness in an immense universe, how could an astounding divine act around two millennia ago ever appear sufficiently probable as to be worthy of belief?
The only way it could become probable, at least the only way that makes any sense to me, is by means of a personal experience that, although non-sensory, has the essential features of a personal encounter. And not just any personal encounter, but one where the encounter and the Being encountered cohere with hints given on the New Testament in a mutually illuminating way, such that it seems compelling that one is encountering God as manifested in Jesus. Such an encounter is not for the idly curious; it requires (or so was my experience) a desire to know passionate enough to overcome a natural reluctance to have your life turned upside down in unpredictable ways of God's choosing.
But what meaning can Christians associate with the immensity of the universe, and the possibility of elaborate forms of extraterrestrial life? Given when they were written, neither the Jewish nor Christian Scriptures address such a possibility. Those Scriptures (as I interpret them) document in various genres a learning experience spread over many centuries. Time and again, a part of the lesson to be learned might be summarized as "your conception of God is too small". If it now turns out that, in the vastness of the universe, God has (so to speak) other fish to fry, and that God's dealings with humanity are but a tiny part of the overall scheme of things, that should excite and fascinate us rather than faze us.