Romans 9:6

Not as though. Paul’s point is that his grief for his fellow countrymen must not be understood as meaning the failure of God’s promise to Israel.

Word of God. That is, God’s declared will and purpose.

Hath taken none effect. Greek ekpipto, literally, “to fall out,” hence, “to fail.”

Not all Israel. The passage reads literally, “for not all who are of Israel, these are Israel.” Paul’s meaning is that not all who are descended from Israel really belong to Israel in the full spiritual significance of that name. His purpose in making this statement is to explain how the word of God to Israel has not failed. The fulfillment of God’s promise is limited to those who meet the conditions of the covenant relation. For this faithful and obedient remnant the word of God will not fail.

Of Israel. This refers to the offspring of Israel according to the flesh, Jacob’s physical descendants. The divine promise was indeed given to Israel, but that did not include everyone who could claim descent from Jacob without any further limitation. Paul has already explained that those who have faith are the true sons of Abraham (Rom. 4; Gal. 3:7-9; cf. Rom. 2:28,29).