Romans 9:6 - Matthew Poole's English Annotations on the Holy Bible

An objection is here obviated: the Jews might object and say: If they were cast off and rejected, then God is unfaithful, and all his promises made to Abraham, Isaac, and Jacob, and their seed, are ineffectual. To this he answers by a distinction of Israelites. Some are Israelites only in respect of their carnal generation; and others, again, are true Israelites, children of the promise, and of the faith of Abraham: see Romans 2:28,29. Now the promises of God were made to the true Israelites, and in all such it is effectual: and under the name of Israel, or true Israelites, all those are comprehended, who imitate the faith of Abraham, and walk in his steps, whether they descended from him by fleshly generation or not. This he further asserts in the following verse.