In "the Prince", Machiavelli writes of two Popes - Alexander and Julius - who "showed how a pope with both money and arms was able to prevail". He refers to the Vatican and similar states as "ecclesiastical principalities", which are sustained through the continued religious impulse of their citizens and neighbors. The idea that even the Pope was a creature of politics shouldn't have been shocking to Machiavelli's contemporaries, since the Western Schism (1378-1418) left Europe with multiple Popes.
Religion has always walked together with power, in one form or another. In the 1970s, "Operation Snow White" was carried out to purge the government's files of a religion that was founded by a science fiction writer. About 5000 covert agents were sufficiently convinced of the authenticity of this religion that they were fine with risking the wrath of the law. In 1977, elements of the Korean intelligence apparatus used a religious movement to gain political influence in the United States, by having Church members volunteer in Congressional offices as staffers. In 1984, followers of an Indian guru organized the largest mundane bioterrorism attack in United States history, by trying to poison the voting population of the city they lived in so that their man could get voted into office. A year later, the investigation into that case uncovered a plot by the same people to assassinate a US attorney.
A few supervillains have spotted the advantages that starting a cult - I'm sorry, a New Religious Movement (NRM) - can bring. While I'm not really on board with doing this, I feel it's my duty as a veteran villain to inform people of what's involved.
Tax exempt status
My friend Dr. Tornadeau says, "the First Amendment has unintentionally created circumstances where the most powerful organization in America is a cult." He's looking at the examples above, as well as more recent NRMs that have been formed and are still thriving today.
A small but well-organized church can move millions of dollars, legally and tax-free. It's been estimated that the Catholic Church - a minority in the US - still moves upwards of 170 billion a year. "But Mr. Big," you ask, "what do you mean estimated? Don't we know?" So now you know one reason supervillains like the idea of starting new religions. Churches can ignore any number of regulatory and disclosure requirements in the United States, and are tax-free for the most part.
Protection from criticism
Churches are notoriously hard to criticize in today's culture. That doesn't stop them from saying any damn thing they want, about any damn person they please, of course.
Big names like Amazon and Google have been pressured to pull materials critical of churches, even when those churches are by any objective measure a fringe presence in the American religious scene. More directly, critics of such churches have found themselves harassed either by church members or members of law enforcement by proxy.
Supers and cults
The superheroine Diver, though she doesn't talk much, is known by a few of us to be a runaway from one cult in the Pacific Northwest, or maybe further north - Canada or Alaska. She was being used as a figurehead of divinity to inspire cult followers. She doesn't claim any supernatural powers or divine blessing, just good old fashioned superpowers.
Singularity had a pretty good apocalyptic cult running before her disappearance. These were the same sorts of people who got into Jim Jones or Heavens Gate - "the aliens are coming, let's all be good people and/or kill ourselves". In such cases, "cult" is still the right term despite "aliens" taking the place of "god". This is nothing new - many, many conspiracy theories have no problem throwing space aliens and Satan into the mixer and hitting "blend".
In general, supers make very convincing cult leaders, and are very difficult to dislodge. The reason is obvious: their claims to extraordinary ability really are true, and most of their claims about origin either can't be disproven, or sound credible enough (in the face of the reality of superpowers) that otherwise-sensible people will buy into them. The strongest threat that such a cult faces is the defeat of its leader by a law-abiding superhero. This is usually enough to break the cult up sufficiently to begin mopping up the lieutenants, but sometimes another super can swoop in and take over the fragments, and build a new flock.