I think aliens would be a tough cookie for our population who believes in an Earth centric universe. I also think of the things that we do and have done to less developed civilizations would not be appreciated by "civilized" people. Of course we can rationalize our hypocrisy, the Pope is used to being very important on the world stage and the tribal medicine man is not. It's reasonable for the tribal medicine man to be an academic curiosity, but the shoe doesn't fit so well when it's on the Pope's foot.
And say, how many Earth gods does it take to destroy an advanced space faring civilization? I don't know. But if I had to guess I don't think we have enough. More gods, stat!