groupophilia 

the tendency or urge to be a part of and accepted by a group of people

Since individuals survive best within a group, groupophilia is a potent motivator of human behavior and is the root cause of peer pressure, social conformity, religion, patriotism, and gangs.

groupophilia by Luke Indago August 6, 2016

groupophobia 

fear or intolerance of groups other than one's own

Donald Trump uses paranoia and groupophobia as a means to motivate his followers.

groupophobia by Luke Indago August 6, 2016