If we look up the word “cult,” we find many different meanings, most of which are pejorative.  Here are two good examples:

a relatively small group of people having religious beliefs or practices regarded by others as strange or sinister.  “a network of Satan-worshiping cults”

a group which is typically led by a charismatic and self-appointed leader, who tightly controls its members, requiring unwavering devotion to a set of beliefs and practices which are considered deviant (outside the norms of society)

As suggested by the meme here, once you’re a member of one of these groups, you’ve proven that you’re susceptible to this type of thinking, making you an easy target for another cult membership.

The Cult of Trump