God spoke Israel into existence along with all its special privileges. God did not speak to no purpose, and his speaking did not fail: But it is not as though the word of God has failed
(Romans 9:6a). By this sentence Paul dispels the idea that things are finished for Israel. Many Jews refused to believe and opted to remain silent with the coming of the Messiah, Jesus. But this did not mean that God was finished with them. His word does not depend on whether the Israelites respond or fail to respond to him. God never breaks his promise.
Cranfield1 also points that the words ouch hoion de hoti (translated by the ESV as it is not as though
) do not refer to an impossibility, but to a fact. The phrase is, after all, still followed by a subject and a verb, not by an infinitive. This reveals that God’s promises concerning Israel can never fail or become void.
6 But it is not as though the word of God has failed. For not all who are descended from Israel belong to Israel,