Nazarenes was name given to those who followed Jesus of Nazareth. Since people knew Jesus as "Jesus of Nazareth" or "Jesus the Nazarene," it was easy to transfer that title to his followers. They were “followers of the Nazarene” or “Nazarenes.”
The earliest use of the term is in Acts 24:5. Tertullus accused the apostle Paul of being “a ringleader of the sect of the Nazarenes.” This was not meant as a compliment.
The early Christians probably did no use that name for themselves. However, later Jewish-Christian and Gnostic groups (religious groups that emphasized special secret knowledge) did call themselves Nazarenes. One early writing was even called The Gospel of the Nazarenes.