Here is another discrepancy. The JWs misstate the relationship between Isaac and Abraham, referring to him as the "only-begotten son" in a procreative sense in attempting to prove that the Word was created, not unoriginated. But because of Ishmael, that term must mean that it applied to Isaac in a religious, legalistic and figurative connotation as he was a legitimate son; it refers to a non-biological, non-procreative relationship just as Trinitarians teach with respect to the Word.
The Jehovah's Witnesses teach that Jesus was “begotten” in the sense that he was created or born, which is not a Christian Trinitarian teaching. The Jehovah's Witnesses write:
Trinitarians claim that in the case of Jesus, “only-begotten” is not the same as the dictionary definition of “begetting,” which is to “procreate as the father.” (Webster’s Ninth Collegiate Dictionary) They say that in Jesus’ case it means “the sense of unoriginated relationship,” a sort of only son relationship without the begetting. (Vine’s Expository Dictionary of Old and New Testament Words) Does that sound logical to you? Can a man father a son without begetting him?
Furthermore, why does the Bible use the very same Greek word for “only-begotten” (as Vine admits without any explanation) to describe the relationship of Isaac to Abraham? Hebrews 11:17 speaks of Isaac as Abraham’s “only-begotten son.” There can be no question that in Isaac’s case, he was only-begotten in the normal sense, not equal in time or position to his father. (Should You Believe, Chapter 6)
Actually, Strong and Vine’s does in fact explain why the very same Greek word for “only-begotten” (monogeneses) is used to describe the relationship of Isaac to Abraham, and how “only-begotten” is used with respect to Isaac at Hebrews 11:17 as subsequently explained in this article.
One major weakness in the Jehovah's Witnesses’ argument lies in the fact that Isaac was not an "only-begotten" son in the natural procreative sense since Abraham actually had another son, Ishmael, (and others after Ishmael) who was born before Isaac (Genesis 16:15), so the Jehovah's Witnesses’ reliance on that verse is unfounded. Because Abraham had no less than two sons, “only-begotten” cannot be applied to Isaac as an “only-begotten son,” in the procreative sense because he wasn’t. It applied to him in a religious, legalistic and figurative connotation as he was the only legitimate son; it refers to a non-biological relationship just as Trinitarians teach with respect to the Word.