The belief system can be many things, this is just from the top of my head:

Natural rights or right to dominate others.

The non-agression principle, religion and whether population growth is good or not.

Do we have global manmade warming, if so how to deal with it.

US hegemony vs national sovereignty. Right to self defence.

Property rights or communism. Individuallism or altruism. Veganism or carnivore.

Respect for public goods such as the high seas and the Bitcoin network.

What and how to teach children, and who should teach them.

Respect for language, logical thinking, laws of physics, or "everything is subjective"/deconstructionism.