KJV alternate rendering of the Greek adjective monogenes (John 1:14,18; 3:16,18; Heb 11:17; 1 John 4:9). Elsewhere the KJV rendered the term “only [child]” (a son in Luke 7:12; 9:38; a daughter in 8:42). KJV, NKJV, NASB render monogenes as “only begotten [son]” when refering to Jesus (cp. NASB margin, “unique, only one of His kind”), but most modern translations (ESV,NAB,NJB,NLT,NRSV,REB,TEV) render the term consistently as “only.” NIV, HCSB render the term “One and Only [Son].”
The term monogenes is related to Greek monos, “only, and genes, “offspring, race, kind,” suggesting the meaning “only one of its kind, unique” for monogenes. Four times the Septuagint (Greek translation of the Hebrew Old Testament) uses monogenes to translate Hebrew yachid, “only” (Judg 11:34) [“only child”]; Psa 22:20 [“my very life”]; 25:16 [“alone’]; 35:17 [“my very live”]}. In Gen 22 referring to Isaac as Abraham’s “only son” (v 2,12,16) and a few other places, the Septuagint rendered yachid with agapetos, “beloved.”
Although unicus, “only,” had been used in the Old Latin to translate monogenes, Jerome (A.D. 340-420) replaced it with unigenitus, “only begotten,: in the Latin Vulgate, from which derives the traditional English rendering. Jermone’s concern was to refute the Arian doctrine that claimed the Son was not begotten but made. This led Jerome to impose the termingology of the Nicene Creed (A.D. 325) onto the NT.
Monogenes is used for an only child (Luke 7:12; 8:42; 9:38), but the writer of Hebrews used monogenes of Isaac with full knowledge that Issac was not Abraham’s only child (Heb 11:17-18). Here monogenes designates Isaac as Abraham’s son in a unique sense, the special child of promise through whom Abraham’s descendants would be named.
Believers are rightly called huioi, “sons” of God by adoption in Christ (Matt 5:9; Luke 20:36; Rom 8:14;19;9:26; Gal 3:26;4:6-7; Rev 21:7), but John used monogense to designate the unique relationship of eternal Sonship that Jesus has with God. Being fully God and of the same nature as God the Father, Jesus the Son alone can make God’s glory known (John 1:14,18 Heb1:1-3). As the “One and Only Son,” Jesus is the unique gift of God, the giving of God’s own self for salvation (John 3:16; 1 John 4:9). Because Jesus is the unique representative of God, rejection of Jesus means rejection of God, resulting in swift condemnation (John 3:18).