If we knew we were not alone in the universe it would have a very, very deep impact on our worldview, on our understanding of our place in the universe.
I believe there's other forms of intelligence in the universe. I've seen and heard some pretty convincing UFO stuff. Besides, if we're the most intelligent things in the universe... well, that's just depressing.
If you knew the immensity of what it means to be human, you would not talk about God or Heaven.
The question is being asked, 'Are we alone?' And though we now focus on that question we need to think beyond that to what if we're not alone? Then what becomes the next imperative question?
Five centuries ago, Copernicus upset humanity's applecart with the news that the Earth is not the center of the cosmos. It could be that, before you've paid off your house, we'll learn that the universe is not the center of the universe, either!
Whatever things may have been in their origin, they are what they are, both in themselves and in regard to their indications respecting other beings or influences the existence of which may be implied in theirs.
In the future, maybe quantum mechanics will teach us something equally chilling about exactly how we exist from moment to moment of what we like to think of as time.
Are we the only members of the Galaxy that can actually understand what a galaxy is? Could Homo sapiens really be the pinnacle of Creation - the cleverest critters in the cosmos? If we learn the answer is 'no,' that would affect our philosophies forever.