One criteria that's fairly defining of a cult, by my definition, is major operational secrecy. People who join don't know what the higher-ups are doing. Indeed, they often don't know the fundamental doctrines of the cult! E.g. people who join Scientology don't get the whole "God is a space alien" package dropped on them until they're many, many $10,000s down the hole already.

Now, let's take Catholicism, probably the major faith most often accused of cult-like behaviour. It certainly has some of the most political structure and (pardon the pun) orthodoxy of the major religions. But Catholicism is also extremely open. There are no fees to join. There are no mandatory payments. There are no doctrinal secrets. They're entirely open about everything they believe, up front. You don't get whacked with some dark secret ten years in. They also don't really attempt to control most, let alone all, domains of of members' lives. They go about careers, etc. as they see fit. They're also tolerant of internal criticism and dissent; you've got some Cardinals in favour of gay marriage, and some of the loudest voices about the systematic sex abuse problem (one of the biggest reasons one might call them a cult) are coming from adherent Catholics, who aren't automatically excommunicated or given other traditionally cult-like handling for their dissent.

Such difference seems very significant to me. And I'm an atheist and decidedly anti-religious, for what it's worth.