1 Jude, a servant of Jesus Christ, and brother of James, to those who are called, sanctified by God the Father, and kept for Jesus Christ
Jude in Hebrew is Judas who was a brother of James and who was the brother Jesus as seen in Matthew 13:55 which says, “55 Isn’t this the carpenter’s son? Isn’t his mother called Mary, and his brothers, James, Joses, Simon, and Judas?”
“to those who are called” is in reference to the elect, who responded to the Lord’s invitation to be their savior.
Those with eternal life are “sanctified by God the Father” because they live for Him and are “kept for Jesus Christ” which means that they will not lose their salvation [John 10:28-30].