Aliens are believed to be smarter, because if one 'visited' us, we would be in awe of themselves and technology.
Nope, not their religion, economic standpoint, or even their personal lives.
We care about how they look, can they talk, are they smart, and can they kill us.
I'm not sure why, but aliens can take some religions on it's head just by description,
especially if they look like us. That itself can make the whole world think they are intelligent.
Who said they weren't anyway? I don't think anyone would object if that happened, unless they saw otherwise...