‘I say then, Did God cast off his people? Certainly not. For I also am an Israelite, of the seed of Abraham, of the tribe of Benjamin.'
In his usual manner Paul raises a question in order to answer it. His question is, ‘did God cast off His people', and it is asked on the basis of the quotation in Isaiah which he has just used, ‘all day long have I held out My hands to a disobedient and obstinate people' (Romans 10:21). His initial answer is that this cannot possibly be so because he himself is one of ‘His people' and has not been cast off (the ‘for' confirms that this is the initial part of his argument in this passage). Thus it is not true Israel who has been cast off, only unbelieving Israel. Indeed a good proportion of the church in 1st century AD were recognised as Jewish Christians. They were ‘the remnant according to the election of grace' (Romans 11:5). They could have been cited as added evidence that God had not cast off His true people, the elect to whom His promises were made (Romans 9:6 onwards). But this was probably something which Paul expected his readers to infer.
So here Paul is powerfully arguing that Israel does continue to exist, even though God has purged it. It continues on in Paul and in the elect among the Jews. It is they who are the true Israel. In contrast modern man disinherits this Israel, and opts for unbelieving Israel as representing Israel. But to Paul ‘Israel' as an existing, continuing, and vibrant entity was represented by believing Jews, supplemented by Gentile converts. While modern man looks to Palestine for Israel (the old unbelieving Israel which was cast off), God (and Paul) looks to the true congregation of Jesus Christ around the world. Here in fact was Paul's dilemma. In order for men to understand what he was saying he had to refer to the old cast off Israel as Israel, for there was no other way in which to identify them. But to him the genuine Israel was the renewed Israel under the Messiah.
‘For I also am an Israelite, of the seed of Abraham, of the tribe of Benjamin.' In these words Paul establishes his credentials. He is an Israelite (compare Romans 9:4), he is ‘of the seed of Abraham' and he is ‘of the tribe of Benjamin'. These were credential which could be demonstrated tangibly. Whilst he may well not have been able to prove that he was a direct descendant of Abraham, something which few Jews could do, he could certainly prove that he was accepted as such on a basis satisfactory to Jews. The fact that he was recognised as being of the tribe of Benjamin explains why he was originally named Saul, for King Saul had been of the tribe of Benjamin.