Primogeniture legal definition of
Why did our Lord Jesus arise from the tribe of Judah?
Response: The book of Hebrews actually uses this very issue to make a point of the fact that in coming from the tribe of Judah our Lord’s new high-priesthood signals a change from the Old to the New Covenant, since of course in accordance with the Mosaic Law all prior priests came from the tribe of Levi (see especially Heb. chap. 7-8). One important reason in the selection of the tribe of Judah for our Lord’s genealogy is the membership of David in that tribe. Jesus, of course, is David’s greater Son, and in the mentions of our Lord’s lineage it is usually His descent from David that is the point which is emphasized rather His tribal affiliation per se (e.g., Matt.1:1; 9:27; 22:42; Lk.1:32; 1:69; Rom.1:3; 2Tim.2:8; Rev.22:16; cf. also Rev.5:5 where “from the tribe of Judah” is immediately reinforced by “[from] the root of David”). For Jesus is the “Son of David”, the One who fulfills the covenant to that great believer wherein he was promised a Son who would reign forever, the Branch who would spring from his root, namely, the Messiah (cf. 2Sam.7:12-16; Is.9:6-7; Jer.23:5-6).
The first and technical reason for Jesus’ descent from Judah is the important fact that Jesus is THE “First-born” unique and only Son of the Father (Rom.8:29; Col.1:15; 1:18; Heb.1:6; Rev.1:5; cf. Jn.1:14; 1:18; 3:16 3:18; 1Jn.4:9), and Judah is the tribe of the first-born – by assignment. For although Reuben was technically Jacob’s first-born son, he forfeited the double-portion rights of inheritance that would otherwise have accrued thereto through misconduct – and he lost them to Judah (cf. Gen.49:3-4; 1Chron.5:1). It is for this that reason the “ruler’s scepter” belongs to Judah (Gen.49:10; cf. Num.24:17), who ever after receives the privileges of the first-born. While we are not specifically told why it is that Simeon and Levi, Judah’s older brothers, were disqualified from taking Reuben’s place, it no doubt has to do with the incident in Genesis chapter 34 (compare especially Gen.34:30 with Gen.49:5-7).
Just as the three brothers ahead of Judah were disqualified for misconduct, so we have a reverse parallel in the case of David who was promoted for extraordinary conduct (specifically, his exceptional love for the Lord). David, of course, was the youngest of the sons of Jesse, and yet because of his heart for God and his dedication to the Lord which put all of his brethren in the shade, he was exalted as no one before him, becoming, in effect, the first-born (for God looks on the heart: 1Sam.16:7). So on this point of “primogenitor”, it is important to remember that God is not only capable of but also inclined to exalt the humble and humble the proud, considering the true “first-born” to be him or her who puts the Lord first in their hearts, demonstrating that faith and dedication in lives of faithfulness. For it is only in carrying our crosses daily in this way that we emulate Him who is the Firstborn of all creation, our dear Lord and Savior Jesus Christ.