While there are many opinions today about who the “true” children of Abraham are, ranging from the “church” today, to ethnic Jews, to those of African descent, I prefer to go back directly to the teachings of Yeshua. According to Yeshua, being a son or daughter of Abraham is equated with being a person of faith in the working of YHWH, not just physical lineage:
[Luk 13:16 KJV] 16 And ought not this woman, being a daughter of Abraham, whom Satan hath bound, lo, these eighteen years, be loosed from this bond on the sabbath day?
[Luk 19:9 KJV] 9 And Jesus said unto him, This day is salvation come to this house, forsomuch as he also is a son of Abraham.
When Yeshua used this phrase, as shown above, it was in the context of someone exhibiting great faith, especially faith in him as the Messiah.
Conversely, when confronted by the Pharisees and Jewish leaders who were clearly physical descendants of Abraham, Yeshua contradicts their fleshly ideas that just because of their lineage they were entitled to the blessings of Abraham:
[Jhn 8:39 KJV] 39 They answered and said unto him, Abraham is our father. Jesus saith unto them, If ye were Abraham’s children, ye would do the works of Abraham.
This shows how the “works of Abraham” are once again equated with faith in Messiah. Since the Jewish leaders did not believe, Yeshua did not consider them in the category of “children of Abraham,” even thought they were Abraham’s physical descendants.
In a similar bold statement clarifying John the baptizer’s view of Abraham’s fleshly lineage, he says the following:
[Luk 3:8 KJV] 8 Bring forth therefore fruits worthy of repentance, and begin not to say within yourselves, We have Abraham to [our] father: for I say unto you, That God is able of these stones to raise up children unto Abraham.
Once again, the Jewish leaders were not believing in the work that God was doing; at that time, preparing people for the coming Messiah. So John hyperbolically states that God can create a “child of Abraham” out of anything, even stones!
From these passages, I believe both John the baptizer and Yeshua defined a “child of Abraham” as someone who exhibited faith in YHWH, just like Abraham did.
Paul also confirms this is an appropriate view of the term when he clarifies this definition of the children of Abraham by writing:
[Gal 3:6-9 KJV] 6 Even as Abraham believed God, and it was accounted to him for righteousness. 7 Know ye therefore that they which are of faith, the same are the children of Abraham. 8 And the scripture, foreseeing that God would justify the [nations] through faith, preached before the gospel unto Abraham, [saying], In thee shall all nations be blessed. 9 So then they which be of faith are blessed with faithful Abraham.
For those of us who believe in Messiah today, we are counted as Abraham’s seed only because of our faith IN MESSIAH; we have no “new” lineage to Abraham, or some mysterious “spiritual” lineage (as if there were such a thing). Biblically speaking, those who exhibit faith in YHWH and his Messiah, just like Abraham, will be counted within the idiomatic expression of believers of all ages for the past four thousand years, known simply as “children of Abraham.”