‘For he is not a Jew [meaning praised], which is one outwardly.’ This is very strongly expressed, expressed in a way that reduces the ethnic Jew to nothing, if he does not have faith as Abraham had faith.
How dangerous it is to rely on human praise. Some hear such praise and say, ‘My brother in Christ approves me, therefore I am safe.’ Certainly the praise of believers is safer than the praise of unbelievers – which is what Paul has in mind here – but neither are to be relied upon. Rather we should seek the praise of God who alone sees all.
Is Paul stretching the term Jew? No, he is not saying that this is his own way of looking at the term Jew, but that it is the only way of looking at the term, the only way God ever intended it to be looked at. Many would not accept this because they had to let go of too much in order to embrace this truth – their imagined righteousness and standing with God. But what they were being asked to let go of was not real.
But how can the law which included so many pointers to the work of Christ be called the letter? Because that, in essence, is what it was. It was a covenant that address the external behaviour of man and commanded external rites and ceremonies (2 Corinthians 3:6-7). Of course we know that the law is spiritual and that these external rites were designed to illustrate spiritual realities, but this was a view of things which the unbelieving majority did not have. It is not called the administration of death simply because, in practice, that is what it turned out to be. It is so named because life must come from an entirely different covenant, which was given to Abraham before, but which continued in force throughout the time of the law.