If God doesn’t have an ethnicity because God isn’t human, then how can Jesus the son of God have an ethnicity as a Jew?
You are right in saying that God has no ethnicity. He is beyond the human species. We read in John 4:24 that, “God is a Spirit.” It was completely the sovereignty of God that moved Him to choose the nation of Israel to be His chosen earthly people. We read in Deuteronomy 7:7-8, “The LORD did not set his love upon you, nor choose you, because ye were more in number than any people; for ye were the fewest of all people: But because the LORD loved you, and because he would keep the oath which he had sworn unto your fathers, hath the LORD brought you out with a mighty hand, and redeemed you out of the house of bondmen, from the hand of Pharaoh king of Egypt.”
The Lord chose the nation of Israel and chose for His Son to be born into this nation of people. He specifically said to Abraham in Genesis 12:1-3, “Now the LORD had said unto Abram, Get thee out of thy country, and from thy kindred, and from thy father’s house, unto a land that I will shew thee: And I will make of thee a great nation, and I will bless thee, and make thy name great; and thou shalt be a blessing: And I will bless them that bless thee, and curse him that curseth thee: and IN THEE SHALL ALL FAMILIES OF THE EARTH BE BLESSED.”
Christ’s earthly mother was Jewish as shown in Luke 1:27 which says that Jesus would be born “To a virgin espoused to a man whose name was Joseph, of the house of David; and the virgin’s name was Mary.” Being of the house of David is in reference to Mary’s Jewish tribe, Judah. It was through the birth of the Lord Jesus that He became a Jew. As God, the Lord Jesus has always existed, but as a man, He became a Jew at birth. Hebrews 7:14 makes this clear in saying, “For it is evident that our Lord sprang out of Juda…” Judah, of course, is one of the twelve tribes of Israel. It is the tribe that the kings came from! In Revelation 5:5, the Lord Jesus is called “the Lion of the tribe of Juda…” Both of the genealogies of the Lord point out His relationship to David. (See Matthew 1:1 and Luke 3:31.)
It is beyond argument that the Lord Jesus Christ is Jewish. But, let us not overlook this important point: He is savior of all the world. John 3:15-18 is so very clear. “That whosoever believeth in him should not perish, but have eternal life. For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life. For God sent not his Son into the world to condemn the world; but that the world through him might be saved. He that believeth on him is not condemned: but he that believeth not is condemned already, because he hath not believed in the name of the only begotten Son of God.” Do you believe in the name of the only begotten Son of God? Acts 4:12 tells us, “Neither is there salvation in any other: for there is none other name under heaven given among men, whereby we must be saved.” (292.6)