The Jews to which Paul is addressing his remarks in Romans 2 are those of the tribe of Judah, who later became part of the Caucasian people. Because so many of those of the tribe of Judah were disobeying God while proclaiming themselves so much better than everybody else because they had the Law, the name of God was being blasphemed, as hypocrisy and disobedience are connected with non-Christians blaspheming the Word of God in another verse in the Bible.
It is the same way with our people today. So many Christians, including those who know who true Israel is, are living lives that are totally not conformed to the ways of our Lord. Therefore, their behavior gives those in the world an unfavourable impression of our Heavenly Father as was happening in Paul's day.