This is the most important and well-known verse in the Bible, but do we consider what that phrase means?
Ultimately the interrelations of the two persons of the Father and the Son in the one God is a mystery, but the verse needs to be opened up.
A few theologians, like Berkoff (p. 89, 93-94) and Frame (pp. 490-96) and the authors of the Nicene creed believe that begotten means that the Father eternally generates the Son. It is vital to say eternally generates because the Scriptures affirm that the Son does not have a beginning. It’s a Father-Son eternal relationship in the Godhead, not similar to the human father and human son, both of whom have a beginning.
Frame suggests, humbly, that begetting is connected with the Son becoming man or the incarnation.
Thus the fact that Jesus was begotten and born in history does give us some hints as to his eternal nature. His earthly begetting images something of her eternal relationship with the Father. I suggest that perhaps the phrase eternal generation could be taken to designate that parallel. To say that the Son is eternally generated from the Father is to say that something about his eternal nature makes it appropriate for him to be begotten in time. (p. 494, emphasis original)
Translation: Parallel: Begetting in eternal heaven without beginning or creating the Son is like the Son being born in the womb of May, conceived by the Spirit, on temporal earth.
Jesus is revealed in the New Testament as the Son, when he was born. As the Son, it was he who was by divine decree chosen to be born on this planet and in human time. The Father ordained his earthly birth. The word Son seems appropriate and suitable to that calling.
However, the details of the divine generation are forever hidden in that God relationship.
Still another interpretation:
Grudem (pp. 1233-34) and Moody (pp. 210-11) have a different and simpler idea about John 3:16.
The key word in John 3:16 is monogenēs in Greek, which had been traditionally translated as “only begotten” because the prefix mon– means “only” or “alone” or “unique.” The second half had been interpreted as “beget” as discussed above.
However, new research shows that the word more accurately means “one-of-a-kind” or “unique” or “in a class by itself” and has nothing to do with begetting or generating. The New American Standard Bible says in the margin at John 3:16 “unique, only one of his kind.” The New Revised Standard Version translates it as “only Son.”
“The only begotten does not suggest a coming into existence, but rather it expresses the uniqueness of the person. Christ was unique as the Son of God, sent by the Father from heaven” (Moody p. 210, emphasis original)
So Jesus is one-of-a-kind who belongs in a class by himself. Therefore the idea of the Son’s eternal generation by the Father is removed, and the interpretation of John 3:16 is simplified and clarified.
My choice: Frame’s ideas are very appealing, but if Grudem and Moody find the evidence, then so be it. If forced to choose, however, Frame is my preference—for now. But Frame is quick to point out that since we are not clear, we should not declare each other heretics or outside of orthodoxy.
So how does knowing about the Trinity help me know God better?
There is an entire ten-point post that answers that question, here:
Written by James Malcolm
ARTICLES IN THE TRIUNITY SERIES
The Trinity: What Does ‘Only Begotten Son’ Mean in John 3:16?