Many of us who memorized John 3:16 as children struggled with the phrase His only begotten Son. It often came out “only forgotten,” to the amusement of our parents. Most modern translations have replaced only begotten Son with phrases like one-and-only Son.
Why is that?
The Greek adjective monogenas (mon’-o-ga-nase’) occurs nine times in the New Testament. In Luke 7, 8, and 9, it clearly refers to parents who were distressed about the illness or death of a one-and-only child. In Hebrews 11, it refers to Abraham’s unique relationship with Isaac. The rest of the occurrences are in the writings of John and refer to the relationship between Christ and the Father (John 1:14 & 18; John 3:16 & 18, and 1 John 4:9).
The prefix (mono) means “one” or “only.” The word “genas” is the word that means race, stock, family, class, kind, or of the same nature.
When the New Testament began to be translated into Latin, the first versions rendered that word with the Latin unicus, meaning “unique”. It was understood that monogenes referred to a unique, dear, one-and-only relationship between a parent and a child.
But at the beginning of the fifth century, the great scholar, Jerome, made a critical change. Perhaps he was influenced by theological lectures he heard or from a concern to protect the orthodox doctrine of the Person of Christ. Perhaps he had the mistaken notation that the Greek word genos was derived from the term gennao, meaning begotten, which it isn’t.
At any rate, in his Latin translation he used the word unigenitus, which meant “only begotten,” instead of the more accurate Latin term unicus, which means “unique,” or “one-and-only.” Jerome’s translation became the standard Bible for a thousand years, and it led many of the early English versions (including the King James Version) to use the term “only begotten.”
Today there is widespread agreement among modern scholars that the word monogenes means unique, precious, one of a kind, one and only; and that seems to be the best translation.
PS – Check out my message from John 3:16 at http://www.donelson.org/pocket/pp-030420.html .