What we call "ETs" are the Angels and Demons of old. I don't believe a confirmation of their existence will replace religion, per say, but I believe that it will explain to us in greater detail the very simple and rudimentary concepts written about in our sacred ancient texts. Humans will understand that they are physical, biological Entities that were "created" by a higher power, same as man was. More powerful, more intelligent, more advanced- but nonetheless, they were made by something and have pursued questions pertaining to their own origins same as us.

Their existence being confirmed does not nullify the question of a Creator or Spirituality- on the contrary, it expounds on those questions. There are "good" and "bad" factions of these species...and it is reasonable to think that these beings probably have their own concepts of Spirituality and Morality- Good and Bad, Right and Wrong.