on'-li be-got-'-'n (monogenes): Although the English words are found only 6 times in the New Testament, the Greek word appears 9 times, and often in the Septuagint. It is used literally of an only child: "the only son of his mother" (Lu 7:12); "an only daughter" (Lu 8:42); "mine only child" (Lu 9:38); "Isaac .... his only begotten" (Heb 11:17). In all other places in the New Testament it refers to Jesus Christ as "the only begotten Son of God" (Joh 1:14,18; 3:16,18; 1Jo 4:9). In these passages, too, it might be translated as "the only son of God"; for the emphasis seems to be on His uniqueness, rather than on His sonship, though both ideas are certainly present. He is the son of God in a sense in which no others are. "Monogenes describes the absolutely unique relation of the Son to the Father in His divine nature; prototokos describes the relation of the Risen Christ in His glorified humanity to man" (Westcott on Heb 1:6). Christ's uniqueness as it appears in the above passages consists of two things: (a) He reveals the Father: "No man hath seen God at any time; the only begotten Son, who is in the bosom of the Father, he hath declared him" (Joh 1:18). Men therefore behold His glory, "glory as of the only begotten from the Father" (Joh 1:14). (b) He is the mediator of salvation: "God hath sent his only begotten Son into the world that we might live through him" (1Jo 4:9; Joh 3:16); "He that believeth not (on him) hath been judged already" (Joh 3:18). Other elements in His uniqueness may be gathered from other passages, as His sinlessness, His authority to forgive sins, His unbroken communion with the Father, and His unique knowledge of Him. To say that it is a uniqueness of nature or essence carries thought no farther, for these terms still need definition, and they can be defined only in terms of His moral consciousness, of His revelation of God, and especially of His intimate union as Son with the Father.
The reading "God only begotten" in Joh 1:18 the Revised Version margin, though it has strong textual support, is improbable, and can well be explained as due to orthodox zeal, in opposition to adoptionism. See Grimm-Thayer, Lexicon; Westcott, at the place