One of the primary questions that arises in the light of a revelation by aliens is “Would religion survive?” The question is more in depth and varied than could possibly be satisfactorily and responsibly answered with a simple answer, but let’s take a bit of a more in-depth look at the factors involved and the groups who would be most affected. In the end, I think we will find that the answer is as complex and dynamic as every individual involved.
To look at several ancient texts, it becomes clear that one of the biggest points of contention that could potentially arise could easily come up within the first few moments after the announcement was made and an open dialogue began between the human race and the extraterrestrial visitors. If the visitors claimed they had just started visiting some time around the sixties, we would have quite a bit to consider, but for the most part Western religion would find it easy to persevere through the ordeal as yet another major change in a world where worldview shattering change seems inexorably commonplace. On the other hand, should these visitors claim an ancient Earthly history that dated back to the points these religious texts had been created, we would almost certainly have serious social fallout from not only the religious, but many historians.
For example, the theory that aliens were the cause of numerous miracles throughout the life of Christ would split major religious denominations three ways. No doubt a third would come to the conclusion that the source of the texts had no standing on their personal beliefs, and continue to believe in the metaphysical version of God they had come to know and worship. The second group would likely believe the claim and swear allegiance to the newly returned. Without extensive proof (and possibly even with) this second group would likely be slow to develop as tradition outweighs change often. The third way, fearful of these mysterious and possibly dangerous newcomers would rebel and likely resent the visitors and in extreme cases react violently. None of these groups pertain to any particular religion and could apply to several denominations of many religions easily. This is more an idea of human nature and behavior than of the religions themselves.
If the visitors did, however, merely claim they had visited and possibly had some influence on historical events but largely withheld information regarding any religious interference aside from those that no longer were widely practiced, the impact would be far different. The transition may begin by declaring that the pyramids had received some help or guidance from ancient aliens, then over the course of generations more information could be subtly introduced. This would likely be a considered course of action taken if the desired result was minimal social upheaval.
A more important question than would generalized religion survive, of course is, “What beliefs of mine would change?” Religion has survived a great deal of change and trial in the past, and there’s nothing suggesting it will go away entirely. Of course change is inevitable as history has demonstrated throughout time.