His brothers said to him, “Are you indeed to reign over us? Or are you indeed to rule over us?” So they hated him even more for his dreams and for his words.
— Genesis 37:8
Jude, a servant of Jesus Christ and brother of James
– Jude 1a
There is a lot wrapped up in this simple greeting, the opening line of Jude's epistle. Jude is the brother of James, by which he means the James, James the apostle, the brother of Jesus. So this Jude is the Jude who is the brother of Jesus. But he doesn't identify himself as such. He calls himself James's brother but Jesus' "servant."
Jesus' kid brother doesn't say, "I'm Jesus' kid brother," but "I'm Jesus' servant." Again, so much is there.
If you're familiar with the biblical narrative even cursorily, you are probably familiar with the younger brother/older brother dynamic that recurs throughout. According to Jewish custom, the oldest son is the honor-bearer of the family. His legacy has primacy. So we see this, as one example, in the law of levirate marriage, which says that if a man dies and leaves a widow, the next younger brother is obliged to marry the woman and thereby continue the lineage of his older brother. In fact, their firstborn would be considered the dead brother's firstborn. (This may be one reason why what's-his-name hands the kinsman redeemer dibs over to Boaz in the book of Ruth.) The older brother is the one owed the birthright.
But if you know your biblical narrative even cursorily, you also know that the honored older brothers throughout the Scripture are blithering idiots. Family after family shows us the younger brothers outwitting, outlasting, and outshining the older brothers. The failure of the older brother to live up to his honorable position begins with Cain, proceeds through Esau to Joseph's brothers and to David's brothers, and culminates in the older brother in the parable of the prodigal son.
What we see is a gospel template gleaming beneath the religious/custom template in each story. God routinely chooses the B-stringers, the scrubs, the alternates, the lowly, the foolish, the weak, and the unassuming to shame the all-stars (1 Cor. 1:27-28). Indeed, of Jacob and Esau, we read, "[T]he older shall serve the younger" (Gen. 25:23). Older brother after older brother offers failure after failure.
Then we get to the prodigal son story and the older brother is put in place not just to show us again the shameful self-righteousness of those whose own honor seeks the dishonor of others but to show us the desperate need for — finally, for once in history — a good older brother. In the accompanying parables — lost coin and lost sheep — somebody goes looking for the item lost. In the lost son parable, nobody goes, certainly not the older brother who is busy in his room writing that hit song, "Alone in My Principles." So who will go? Who will seek out the lost and rescue them?
The good older brother. The only good older brother. Jesus.
So Jude is perhaps looking at his older brother, the brother whose claims he apparently disbelieved until his brother returned from the grave with a glorified body, and says to himself, "Finally an older brother worthy of the name!" He is the only begotten Son of God (Jn. 3:16), the head and the beginning and the firstborn from the dead, that in everything he might be preeminent (Col. 1:18). Jesus' sheaf is elevated and his younger siblings' sheaves are bowing to it, the sun, moon, and stars encircle him in worship. Jude says of the one who is not ashamed to call us his brothers (Heb. 2:11), "I am not worthy to call my brother my brother. I am his servant!"
And we are his brothers if we will submissively acknowledge his birthright. Jesus is the older brother who does his job. Everybody else is the other guy.