Main point summary
You who are called Jew, teach others the will of God but you are not doing what you teach. Your inconsistency causes God's name to be blasphemed among the Gentiles.
Indeed * you are called a Jew,
and * rest on the law,
* and make your boast in God,
and * know His will,
and * approve the things that are excellent,
being instructed out of the law,
and * are confident
that you yourself are a guide to the blind,
a light to those who are in darkness,
an instructor of the foolish,
a teacher of babes,
* having the form of knowledge and truth in the law.
* You, therefore, who teach another,
do you not teach yourself?
You who preach that a man should not steal,
do you steal?
You who say, “Do not commit adultery,”
do you commit adultery?
You who abhor idols,
* do you rob temples?
You who * make your boast in the law,
do you dishonor God through breaking the law?
For * “the name of God is * blasphemed among the Gentiles because of you,” as it is written.
Difficult. At first, 21a to 21b... seemed to be concessive: You teach others, but you do not teach yourself, etc. But this does not fit with the inference 17-20 to 21-23. The flow is that since they are Jews and know God's will, they should obey it and not only teach it to others. That is why a conditional relationship is the better to go with. E.g. You, therefore, if you teach others, then you should teach yourself too. If you preach that a man should not steal, then you yourself should not steal either etc.
Paul makes another strong point that proofs that the Jews are guilty as the Gentiles. The Jews know the will of God, but cannot follow it. Men is guilty before God, no matter which nationality or religious background he belongs to. Have you personally admitted your guilt to God already?
Flow of thought Options for 17-20 to 21-23 are inference, conditional, Situation-Response. Options for 21a to 21b etc. are conditional and concessive. Option #1 It would be possible to use a situation-response for 17-20 to 21-23 and than choose the concessive for 21a to 21b... E.g. And you teach another, but do not teach yourself. You preach that a man should not steal, but you steal yourself. Verse 24 shows the consequence of that inconsistent behavior, that is that God is blasphemed among the Gentiles. Option #2 The flow could be that since they are Jews and know God's will, they should obey it and not only teach it to others. That is how a conditional relationship is possible for 21a to 21b... E.g. You, therefore , if you teach others, then you should teach yourself too. If you preach that a man should not steal, then you yourself should not steal either, etc. This flow of thought makes it difficult to relate to verse 24. The conditions from 21a to 23b do not stress the problem and contradiction as a concessive does. Therefore, I believe option #1 is the one to go with.