Romans 2:23

‘You, who are boasting in the law, are through your transgression of the law dishonouring God.'

This may in fact be a question (‘are you through your transgression dishonouring God?') or a statement ('you are through your transgression dishonouring God'). But whichever it is, it is applying what he has said above. They boasted in the Law, and yet through breaking it they dishonoured God, for God would be judged by outsiders on the basis of whether teachers of the Law followed their own teaching of which they boasted. Their very boast concerning the knowledge of the Law was thus bringing God into disrepute because of their hypocrisy.