BROTHER. 1. A male person related to another person or other persons by having the same parents (Gen.27.6) or the same father (Gen.28.2) or the same mother (Judg.8.19).
2. A man of the same country (Exod.2.11; Acts.3.22).
3. A member of the same tribe (2Sam.19.12).
4. An ally (Amos.1.9).
5. One of a kindred people (Num.20.14).
6. A coreligionist (Acts.9.17; 1Cor.6.6); often, Christian disciples (Matt.23.8; Rom.1.13). Someone spiritually akin (Matt.12.50).
7. A fellow office-bearer (Ezra.3.2).
8. Someone of equal rank or office (1Kgs.9.13).
9. Any member of the human race (Matt.7.3-Matt.7.5; Heb.2.17).
In the NT the common Gr. word for “brother” is used exclusively, ἀδελφός, G81, which appears over 100 times, the most frequent being in Matthew’s gospel. Although a broader definition of the word is apparent in the NT, possibly due to the broader definition of the Gr. word, yet the responsibilities of brotherhood are much the same as those of the OT. The often sought notion of the innate brotherhood of all mankind is not supported by the usage of the term in the NT. The teaching of Matthew 12:50, “For whoever does the will of my Father in heaven is my brother,” is the primary definition of the term in the other references where it is used. In the epistles it is a straightforward substitute for fellow Christians (Eph 6:2, et al.). The responsibility for mutual love, compassion and respect within the Christian community are stipulated in 1 John consistently in terms of “brother” to “brother.”
International Standard Bible Encyclopedia (1915)
Used extensively in both Old Testament and New Testament of other relations and relationships, and expanding under Christ’s teaching to include the universal brotherhood of man. Chiefly employed in the natural sense, as of Cain and Abel (Ge 4:8); of Joseph and his brethren (Ge 42:3); of Peter and Andrew, of James and John (Mt 10:2). Of other relationships:
(1) Abram’s nephew, Lot, is termed "brother" (Ge 14:14);
(2) Moses’ fellow-countrymen are "brethren" (Ex 2:11; Ac 3:22; compare Heb 7:5);
(3) a member of the same tribe (2Sa 19:12);
(4) an ally (Am 1:9), or an allied or cognate people (Nu 20:14);
(5) used of common discipleship or the kinship of humanity (Mt 23:8);
(6) of moral likeness or kinship (Pr 18:9);
(7) of friends (Job 6:15);
(8) an equal in rank or office (1Ki 9:13);
(9) one of the same faith (Ac 11:29; 1Co 5:11);
(10) a favorite oriental metaphor used to express likeness or similarity (Job 30:29, "I am a brother to jackals");
(11) a fellow-priest or office-bearer (Ezr 3:2); Paul called Sosthenes "brother" (1Co 1:1) and Timothy his spiritual son and associate (2Co 1:1);
(12) a brother-man, any member of the human family (Mt 7:3-5; Heb 2:17; 8:11; 1; Joh 2:9; 4:20);
(13) signifies spiritual kinship (Mat 12:50);
(14) a term adopted by the early disciples and Christians to express their fraternal love for each other in Christ, and universally adopted as the language of love and brotherhood in His kingdom in all subsequent time (2Pe 3:15; Col 4:7,9,15).
The growing conception of mankind as a brotherhood is the outcome of this Christian view of believers as a household, a family (Eph 2:19; 3:15; compare Ac 17:26). Jesus has made "neighbor" equivalent to "brother," and the sense of fraternal affection and obligation essential to vital Christianity, and coextensive with the world. The rabbis distinguished between "brother" and "neighbor," applying "brother" to Israelites by blood, "neighbor" to proselytes, but allowing neither title to the Gentiles. Christ and the apostles gave the name "brother" to all Christians, and "neighbor" to all the world (1Co 5:11; Lu 10:29 ff). The missionary passion and aggressiveness of the Christian church is the natural product of this Christian conception of man’s true relation to man.
See also FAMILY RELATIONSHIPS.
Dwight M. Pratt