Contrarian

Many people call themselves "free thinkers" but are actually contrarians who define most of their positions in opposition to a perceived enemy rather than their own reasoning or evidence.

Trolls are the classic contrarians, and their influence on social media and Internet culture has infected a significant amount of normal discourse. Atheists are contrarians when it comes to religion. And a lot of the right wing internet is contrarian because it exists as a critique of liberalism rather than the promotion of any positive alternate ideology.