Perfect Society.

Imagine this. We receive word from an alien entity that they are ready to begin relations with us. No, not that kind of relations. Get your mind out of the gutter for now. The entity says that they will only share their technologies/knowledge (assume they are superior here) if we can decide on ONE language, ONE set of laws, and ONE ideal. Also, if we choose poorly, we may face annihilation. Your job is to design the perfect order. Without prejudice to your own nation, what ideas could all mankind unite under (if possible)? Go.