A phrase that is often used to describe Jesus in Christian language. The term, often translated as "only begotten," does not mean "born" or "begotten." Instead, it means “the only one of its kind” or “unique.” This is clear from its use in the New Testament and the Septuagint (the Greek translation of the Old Testament).
In the New Testament, the Greek word for this phrase appears nine times. However, only five of these instances, all in the writings of John, refer to Jesus (John 1:14, 18; 3:16, 18; 1 John 4:9). Three of the other occurrences describe an only son or daughter (Luke 7:12; 8:42; 9:38; compare Judges 11:34 in the Septuagint).
Since it often refers to an only child, it implies something special, favored, or precious. The other non-Johannine reference, in Hebrews 11:17, speaks of Isaac as Abraham’s “favored” or “unique” son. Isaac was not Abraham's "only begotten" son. Abraham had other children. But, Isaac was the son through whom God’s promise was fulfilled.
In the Septuagint, the word is used in Psalm 22:20 and 35:17, where the psalmist, asking for deliverance, refers to his soul as something of great value. The Hebrew word behind these Old Testament texts also means “only” and does not suggest birth.
When the word is applied to Jesus, it means not “only begotten,” but “only” or “unique.” The phrase is used with “son” and should be understood as God’s only Son, emphasizing both God’s favor toward him and his uniqueness (John 3:16, 18; 1 John 4:9). At Jesus's baptism and transfiguration, God says, "This is my beloved Son." The Synoptic Gospels share this idea. In fact, in the Septuagint, the word “beloved” is sometimes used as a translation of the word “only” in Hebrew.
In John 1:14, the word “only” is used alone to stress that the incarnate Word (Jesus), in becoming human, is unique and comes from the Father. The final reference (John 1:18) is particularly interesting because some texts say “the only son,” while others say “the only God.” Scribes could have easily written "only son" due to their familiarity with other texts in John. Given the stronger support for "only God," this reading is preferred. The highest possible attitude is shown toward the incarnate Word (Jesus) who became human. No one has ever seen God, but the unique (or only) God, who is close to the Father, has revealed him.