When there is an internal dispute within a religion, a small group of members may leave to form their own branch. Some of these branches have turned into legitimate religious institutions, but others have continued to be labeled as cults. Cults in the modern world have a negative connotation, and this is often due to their policy of isolationism. They keep their members segregated from the community at large, and many forbid interaction with former friends and family members.
While there are cults that have taken hold and grown into legitimate off-shoots of other religions, few have managed this distinction. The Lutheran Church is one group that might have been called a cult, but it now has a long established history as well as being considered legitimate. It never isolated its members from family or friends, and its practices have remained much the same as the Roman Catholic Church from which it sprang.