Jude

In the New Testament, there were two Judes. One Jude, aka, Judas, was one of the original Twelve Apostles (see Luke 6:16). The second Judas was the brother of Jesus (see Matthew 13:55).

It seems that Jude originally planned on writing a more general treatise about the Gospel to a group of Churches. However, when news of the sudden appearance of a heresy within these Churches, Jude was prompted to instead issue a stern warning regarding this threat.