Atheists can be as dickish as any of the religious, or even more (*cough* communists). Don't bet on the "glorious enlightened technologically advanced aliens", they'll cook up an excuse to kill us off and use Earth's resources up in short order, regardless of their professed worldview.ChromaticWolfen said:The religious Humans and Aliens may do that but what about the atheist ones? Maybe we will all come together and bugger of to another planet to live in peace. Also if hey did breath a different type of air then they could wear tanks on their backs like grunts from halo and they would need to visit a special station to top up on their air. Humans would need to do the same on alien planets. Lets not forget that maybe 200 years in the we could surgically altar ourselves to breath both types of air.Twilight_guy said:Cultural friction. Alien and human society has a completely different cultures. We kill each other over which god we believe in what do you think happens when an alien with a completely different comes around. Mass effect has a thin clock for racism for a reason, cultural friction would exist and it does cause racism and hate.
Aside from that, if the aliens aren't humanoid carbon based oxygen breathers they may need special facilities to live and survive and that may cause problems and isolate the two of us.
I know one example makes for poor statistics, but if the only sapient species we know is any indication, the central driving force for the aliens will be greed. Everything else is just making up excuses.
One thing that could stop them from wiping us out would be biological differences making plans for a planet-scale invasion too costly (as if it wasn't unimaginably costly already). Better then to establish trade relations, then win our resources over politically.