When does a Religion Become a Cult?
The answer is very simple: a religion helps its members live their lives, but a cult controls its members' lives.Religions (both Christian and otherwise) provide people with a number of things, such as a sense of community, an explanation for how the world works, methods for interacting with the divine, and guidelines about how to live a good life. Many also explain what happens after death.
But a religion usually takes a hands-off approach: followers are allowed to manage their own lives however they want, as long as they observe the religion's important rituals and avoid wrongdoing.
A cult, on the other hand, tries to manage how its members live. They try to govern how their members dress, how they style their hair, and what they can do with their spare time - assuming they have any. It's pretty common for these groups to keep people busy with different group projects, and some actively discourage careers or activities that would limit how much time someone could spend with the group.
This lack of personal freedom is the simplest way to tell a religion and cult apart.
As an aside, this possessiveness isn't restricted to religious groups. There are many businesses and political groups that operate in similar ways, and they are just as dangerous. That's why many people have come to prefer the term "high demand group" instead, as it highlights the core problem rather than the religious aspect.