The Nazarenes were members of an early Gnostic Christian sect, who followed Jewish laws and abstained from certain 'unclean' foods, wine, and any contact with the dead (necromancy). They accepted the virgin birth and divinity of Jesus.
According to Acts 24:5, the spokesman for the high priest called Paul a ringleader of sect of the Nazarenes. This is not impossible, because several of the early Gnostic Christian sects looked to Paul for inspiration, but it is usually read as a reference to Christians in general.
The Nazarenes were mentioned by several of the early Church Fathers, but not later than the fourth century CE.