If we think of religion objectively we realize that it is a solely human creation because there is not one shred of evidence to ssupport supernatural phenomenon which makes up the building blocks of theistic religion. Therefor, if we were to discover alien intelligent beings, that would shatter the species-centric concept of the human creation of religion.
The Bible may only explain the creation of the Earth and its features and life, but it does not refute the existence of any other planets with life. The Bible simply only describes Earth's creation story without really touching the rest of the universe. If we did make contact with extraterrestrials, I can guarantee that many churches would make moves to convert them, and would, therefore, spread the religion further out. However, the discovery of extraterrestrial life more advanced than us could put Genesis into an even more awkward situation than it already is, and that book of the Bible may have to be looked at in a solely metaphorical light until any hard evidence is attained for any of it.
Honestly, the only thing that will happen is that the religious organizations will scramble to adapt their religious views to the societal norm change. This happened before with the rejection and then acceptance of mixed race marriages. Theism has an uncanny ability to pull the eyes over its followers by adapting texts to make its point. Its amazing how much misinterpretation actually exists in the so called holy and perfect texts.
This whole thing about the discovery of alien life shattering religious faith is socially constructed. There are religious implications only because some people say so. In my opinion, discovering life elsewhere in the universe might prove the existence of a higher power. If God created life on Earth, He is capable of creating life elsewhere.